This is what actually happens to your body when you drink alcohol and swim.

Alcohol and water don’t mix.

Last night two young men tragically lost their lives when they attempted to swim across a Melbourne lake, after a night of drinking with mates.

According to the Royal Life Saving Society of Australia alcohol contributes to at least 20 per cent of all adult drowning deaths every year.

This figure is even higher for people aged 15-29, with 41 per cent of all drowning deaths in this age group attributed to intoxication.

However, the overall figure is likely to be even higher as blood alcohol levels are not always tested when someone drowns.

Drinking before swimming is always a dangerous choice because the alcohol distorts your perception of risk and your own abilities.

It impairs your judgement and increases your risk taking behaviour. Alcohol removes your inhibitions and you start taking bigger risks and making the kind of life threatening choices that you would normally avoid.

Drinking numbs the senses – especially your sight, sound and touch. This leads to unsteadiness and increases your inability to climb or swim or get yourself out of trouble.

Drinking and swimming also produces immediate physical changes in your body. Image via iStock.

Your reaction time starts to slow down when a quick response is vital for survival. Alcohol is a depressant and it reduces the rate your brain processes information.

Alcohol also reduces the effectiveness of CPR, meaning that if you do get into trouble in the water, you may not be able to be resuscitated.

Drinking and swimming also produces immediate physical changes in your body.

Alcohol combined with a sudden change of temperature, such as entering water, can lead to a change in the fluid in your inner ear, causing disorientation.

In cold situations your body will attempt to draw blood away from your limbs and towards your vital organs to prevent heat loss. Alcohol prevents this from happening, meaning you have an increased chance of hypothermia.

Drinking alcohol also increases the chance that a spasm of your vocal chords will occur, snapping the airway shut and locking it closed, which means water will be trapped in your windpipe.

When you add all of this up, you can see how drinking and swimming can quickly lead to the tragic loss of young lives.