Understand the Risks

Whether this is your first time or you’re a veteran of the event, swimming 20kms is no easy feat. That’s why we’ve included this important information along with some expert advice to help open your eyes to the medical risks of the South32 Rottnest Channel Swim. Here, you can also find out the precautions you should be taking, as well as how to spot and act on any potential health issues.

Videos from the experts

Professor Ian Rogers is an expert in hypothermia and pulmonary oedema. The video below outlines the signs of hypothermia and how to manage it, as well as the dangers of developing pulmonary oedema. For more detailed information, see our medical notes section on hypothermia further below.

Professor Rogers has also outlined the medical risks of swimming to Rottnest and tips for a safe channel crossing.

John Muir successfully made the crossing solo and experienced both hypothermia and a heart attack. This resulted in him developing pulmonary oedema during his swim.

Swim Induced Pulmonary Oedema (SIPE)

What is it?

Pulmonary oedema occurs when fluid collects within the airspaces (alveoli) of the lungs. Although it’s uncommon, it can occur in open water swimmers and we have had cases occur in the Rottnest Channel Swim. The condition is often referred to using the American acronym of SIPE (Swim Induced Pulmonary Edema).

What are the symptoms?

The symptoms include a cough with frothy sputum (combination of saliva and mucus) which can contain blood, and increasing shortness of breath (worse than what would normally be expected during the swim). The competitor will usually be aware of this themselves unless they are impaired for some other reason (such as hypothermia).

What should I do if I or a team member gets it?

Once the condition is recognised, the swimmer must be removed from the water and helped to get warm and dry. They should be kept sitting up, as lying down will worsen the shortness of breath. These measures are often enough to relieve the worst symptoms, but medical care will still be needed – call Channel Swim base.

Shoulder the load: Avoiding and managing swimmer’s shoulder

Other than insanity, swimmer’s ear, stings, neck pain, chaffing and rashes, the most likely problem you’ll experience whilst preparing for or doing your Rotto swim is swimmer’s shoulder. It’s a good idea to know how to prevent it, as well as the signs, as it could affect your preparation or swimming on the day.

What is swimmer’s shoulder?

Bursitis, rotator cuff tendonitis and impingement syndrome are all loosely in the diagnosis of swimmer’s shoulder. The problem is the breakdown or degeneration of the tendons (rotator cuff) or inflammation of the protective lubricant sacks (bursa) around the shoulder joint.

The repetitive “friction” and loading on the shoulder structures as they pull your body through the water during freestyle, particularly with a poor swimming technique, can cause the problem. The risk with butterfly is higher, with breaststroke and backstroke lower.

Swimming is not the only cause of swimmer’s shoulder – an inappropriate gym program can start it, too. A gym program should be aimed as much at reducing injury risk as making you swim faster. It’s a good idea to get advice from someone with insight into swimming needs and risk.

Is swimmer’s shoulder preventable?

Yes. In most cases you can significantly reduce your risk of problems – it’s usually related to your freestyle technique. Getting skilled advice and changing your stroke technique will significantly reduce risks. There are also some simple strength and flexibility exercises that help – we’ve given you some instructions. However, you may need your shoulder assessed by a physiotherapist with knowledge of swimming who can recommend specific exercises. Keep in mind that what’s worked for your mates might not work for you.

What does it feel like?

If you start getting shoulder pain during or after your swims, do something about it immediately – it’s likely to get worse. You might notice some pain initially when you warm up or do a sprint, usually in the shoulder or upper arm. If you also get pins and needles/tingling anywhere in the arm, your neck may also be involved. If things worsen, you’ll notice pain on movements behind the line of the body and overhead. The pain could increase so you notice it at night, particularly if you lay on the painful side. Ultimately, worsening pain will force you to stop swimming.

Stop it before it starts

The best thing to do is to prevent the onset of any symptoms. Here’s how to significantly reduce your risk of swimmer’s shoulder:

  • Pre-training muscle/posture assessment and advice from a ‘swimming smart’ physio
  • Use the exercises we provided earlier (but you may require some more specific advice)
  • Correct your stroke
  • Use a simple pre-swim stretch program
  • The right gym program – remember, the aim of this should be to avoid injuries as well as making you swim faster
  • If you start getting symptoms, early management is crucial. Don’t let the problem worsen before getting advice

See a professional (e.g. physio) if you notice any issues.

Important medical notes

Dr David E Davies (MBBS., FANZCA., Dip.DHM.) has kindly provided these medical notes about issues that can affect you on the Rottnest swim – it’s important to be aware of the risks you could face.

Heat illness

During exercise, it’s important that the body’s core temperature is kept within a narrow range. If this temperature moves outside of this range, the body’s capacity to perform strenuous physical activity is reduced.

When exercising in hot conditions the body attempts to regulate body temperature mainly by sweating and evaporation. Swimmers need to be aware that if the conditions on the day of the swim are humid, these heat regulation mechanisms are not as effective.

Swimmers who are in teams can prevent heat illness by wearing light weight, well ventilated clothing while not swimming, spraying water on their skin and exposing the body to air flow. Swimmers can keep cool by taking regular drink breaks and scheduled rest breaks. All swimmers should try and stretch to help relieve muscle cramps.

Heat illness has 3 separate degrees of severity:

  • Dehydration – symptoms include loss of energy, muscle cramps, thirst, diminished performance and headache.
  • Heat exhaustion – symptoms include headache, nausea, feeling faint of dizzy, cramping, chills and clammy skin.
  • Heat stroke – is characterised by high body temperature, confusion or loss of consciousness.

To treat dehydration and heat exhaustion drink fluids, lie the swimmer down and rest the swimmer under shade. If their condition deteriorates, seek medical help immediately.

If a swimmer is showing signs of heat stroke, remove them from the water, seek immediate medical assistance, lie the swimmer down under shade and cool them by applying wrapped ice packs to the armpits and/or groin.


Humans can cool 4-5 times faster in water compared with air at the same temperature. Although the water temperature in the Perth area in February is 20-22 degrees Celsius, a number of swimmers still get cold during long ocean swims.

Blood vessels in the skin contract in cold conditions, unlike blood vessels in the scalp – which is where most heat is lost. It’s a good idea to wear a bathing cap that doesn’t allow water through it under the official race cap to minimise this heat loss.

During a long swim the body temperature is maintained largely by metabolism in the muscles. If the muscles don’t receive enough energy, they won’t work as well and will generate less heat. It’s essential to make regular, short stops to replace this energy by eating and drinking warm high-energy foods and fluids. Digestion generates heat while supplying energy to the muscles for maximum efficiency.

Nutrition stops should be kept brief to reduce heat loss from a lack of muscle activity. It’s the support crew’s duty to watch out for signs of hypothermia in their swimmer at all times. In the early stages of hypothermia, even before the swimmer feels cold, the swimming action may become uncoordinated and the swimmer may be unable to maintain a straight course. During food stops, the swimmer may be shivering uncontrollably, appear vague, unable to concentrate or to understand instructions, or acting irritably and irrationally. As the hypothermia progresses, the swimmer may be unable to raise their head or arms out of the water, unable to obey commands or answer questions appropriately. If this is the case, the swimmer should be removed from the water immediately.

Children and seniors are more susceptible to hypothermia and should be watched closely. The hypothermia patient should be handled gently, as rough handling can result in heart rhythm disturbances. Remove the swimmer from the water as gently as possible. They should then be dried, wrapped in a large plastic bag/sheet (for insulation) and then wrapped in towels and blankets out of the wind. Shared body heat might also be a good idea.

If the swimmer is conscious they should be encouraged to eat and drink small quantities of warmed fluids frequently. Avoid alcohol, as this will increase heat loss. If the swimmer is unconscious, place them in the coma position, clear the airway, and don’t give fluids or food. Seek urgent medical attention from a doctor on the course.

Any swimmer who is thought to be suffering from hypothermia must be seen by a doctor as soon as possible.

Marine stings

Stings from marine jellyfish are a way of life in open water swimming. It can be problematic if a sensitive area is stung such as the cornea of the eye, or if the tentacle becomes trapped inside bathers. It’s strongly recommended that swimmers wear goggles at all times while in the water.

Luckily, no marine jellyfish in the Perth region are lethal. The most common nasty jellyfish around Perth is Carybdea rastoni, locally know as a ‘stinger’. Its tentacles are approximately 10cm long but the body is only 1-2cm across. It’s almost transparent and very difficult to see in the water. In summer, stingers can be in large numbers along the beach. This jellyfish tends to swim closer to the surface at dawn or dusk and during cloudy periods. In bright sunshine it swims deeper.

The sting causes an immediate severe burning sensation of variable intensity that may last for several hours, but usually recedes over about 30 minutes while the swimmer is in the water – but it may return when the swimmer leaves the water. This is associated with a skin wheal that may persist for one to two weeks, with minor skin discolouration persisting for several months. Some individuals may also have an allergic response to the sting.

Management of the sting is to initially douse the area of the sting liberally with vinegar then apply ice directly to the wheal to ease the pain (vinegar destroys still-active stinging cells). A cold shower has the same effect as applying ice. Do not rub the area with sand as this causes more toxin to be absorbed. Temporary relief may be obtained from ‘Stingose’, or a roll-on underarm deodorant applied to the wheal. A local anaesthetic cream or spray may help if the pain persists and, for severe wheals with skin damage, a steroid cream such as Betamethasone or hydrocortisone may be indicated.


Seasickness is common among open water swimmers, especially in rough conditions. This is probably due to the motion on the water surface combined with the swallowing of salt water and fuel residue.

Management of seasickness is initially reassurance and possibly altering the breathing pattern to reduce the intake of salt water. If vomiting persists there is a real possibility of dehydration and cramp. A swimmer who is persistently vomiting will probably need to be withdrawn from the water.

A swimmer can reduce the susceptibility to motion sickness by undertaking long training swims in the ocean prior to race day. This is not always effective as sea conditions are infinitely variable, however it does help. Medication may help but if you do use something, make sure you try it out before race day as most of the motion sickness medications have side effects. These side effects can range from dry mouth through amnesia, hallucinations, blurred vision, to severe migraine headache depending on the drug and dosage. Consult your medical practitioner well ahead of time for advice.

Support crew who suffer seasickness should try sitting on the deck close to the waterline and watching the horizon. Being overdressed, too warm, in a stuffy environment, eating too much, and drinking alcoholic drinks will aggravate seasickness. A seasick person should be lightly dressed, slightly cold, have plenty of fresh air, eat small amounts of dry digestible food before and during the crossing and avoid alcohol.

Please note

It is not the responsibility of official boats to transport seasick passengers to shore.


Perth has a reputation for being one of the sunniest cities in the world and there is little atmospheric protection from the sun’s rays. The average temperature during the day in February is 30 degrees Celsius and the ultraviolet factor is extremely high.

The sun will burn in the same way as fire, except we are not aware of the burning sensation. People with fair complexions are most susceptible to sunburn and should take extra precautions. Sunburn can occur even after a relatively short exposure, especially during the middle of the day. Frequent application of a water resistant, sun protection cream (UV factor 16 or higher), a wide brimmed hat and cool, loose fitting cotton, long sleeved shirt is recommended.

Solo swimmers should apply sunscreen at least 15 minutes before wool fat so that it is not washed off – Zinc cream seems to wash off less rapidly than most other creams. Take care to apply sunscreen to all exposed parts such as the face and nose, behind the ears and the neck, backs of the knees/thighs and the soles of the feet.

Reflected sunlight from the water can create problems, and support crews should apply sunscreen to exposed areas, even though they are wearing a hat. Remember, a peaked cap does not provide protection to the sides of the face, the ears or the back of the neck.

The consequences of severe sunburn are dehydration, severe pain and a possible stay in hospital. Most cases of sunburn can be dealt with by taking a cool bath or shower, and applying cool compresses (although not iced as this may chill) to the most affected parts. Calamine lotion or one of the commercial anti-sunburn moisturising creams will usually help. Paracetamol may reduce the pain, but if the sunburn is severe, cold shivers and a temperature may develop. If the sufferer is a child, medical advice may be necessary.

Sharp trauma

There is a risk that the propeller of the escort craft can cause injury, especially in rough conditions and when the boat is manoeuvering close to the swimmer or during team changes. It is the responsibility of the boat skipper to keep clear at all times.

Should any form of cutting injury occur, remove the swimmer from the water immediately, elevate the affected area, cover with a clean towel and apply direct pressure to the wound to stop the bleeding. Seek medical attention urgently from the doctor on course.

Blunt trauma

Blunt trauma to a swimmer is only likely if, in rough conditions, the escort boat gets too close to the swimmer and is dumped onto the swimmer by a wave. Management will depend on the severity of the collision and the condition of the swimmer. If there is any head injury, however minor, the swimmer should be withdrawn from the water and be seen by a doctor on the course.


Exhaustion is characterised by a floundering action where a swimmer is unable to raise his/her arms or is not responding to questions or directions. Taking the swimmer from the water will usually see him/her recover from this problem. A doctor should examine the swimmer as a precaution against a more serious injury.

Administration of medications by non-medical persons

All medications, including prescription and those available over-the-counter, can have serious side-effects. These side-effects may become a problem when the body is placed under additional stress caused by physical activity.

For more information about the administration of medications by non-medical persons go to the Sports Medicine Australia website.