Choose the right place
Use a recognised swimming location where open-water swimming is permitted. Avoid swimming alone or entering unfamiliar water without understanding the conditions.
Open water feels different from a pool. The water moves. You can't see the bottom. There are other swimmers around you. And your normal pool routine suddenly disappears.
That's exactly why your first open-water experience shouldn't happen on race morning.
You don't need dozens of sessions. You need enough experience that the environment stops feeling completely new.
Use a recognised swimming location where open-water swimming is permitted. Avoid swimming alone or entering unfamiliar water without understanding the conditions.
Look at the weather, water conditions and any local warnings before you go. If conditions don't look right, don't swim.
Swim with someone else or use a supervised open-water venue. Tell someone where you're going and when you expect to be back.
Before getting in, identify where you can safely leave the water. Knowing where the nearest exit is can make the whole session feel more controlled.
Don't try to recreate a race on your first visit.
The goal is simply to become comfortable being in open water.
Spend some time getting used to the temperature, the sensation of the water, your breathing and the fact that you can't see the bottom.
Once that starts to feel normal, gradually increase the amount of time you spend swimming.
Lift your eyes forward occasionally while swimming so you can practise finding your direction without stopping completely.
Practise breathing when another swimmer is nearby. Getting used to movement around you can make race conditions feel much less surprising.
You may occasionally touch another swimmer. Practising this sensation in training can stop it feeling alarming on race day.
Practise beginning slowly rather than immediately trying to swim at race pace. Find your breathing rhythm before increasing your effort.
You don't have to push through panic.
Stop swimming. Roll onto your back if that's comfortable for you, control your breathing and give yourself time to settle.
The purpose of training is to build confidence, not prove that you can tolerate something that feels unsafe.
Your final sessions should look increasingly like the environment you'll encounter on race day.
Practise swimming continuously. Practise sighting. Get comfortable with your wetsuit if you're racing in one. And, where appropriate, experience swimming with other people around you.