When the player's strength is low (when he wakes up on Eden, near Outpost Draco), he can only swim a tiny distance before drowning. Beginning players are often frustrated that they can drown in a small pond or while crossing a small river. Fever dramatically increases the chance of drowning.
When drowning starts, vision will blur and start to go grey, then Robert will sink into the water. You shoud exit the water the water as soon as possible or you will die. Drowning happens at shorter times and for longer after the first. Robert will drown on the third sequence.
Endurance Poor: First 'drown' sequence starts at 4s
Endurance Normal: Drowns at 1m 25s
The Creature can't swim long distances, so with the right drugs and medicines, the player can swim to escape it. However, be aware thirst and the subsequent fever shortens your ability to swim. If the player is not prepared, thirst and fever can occur while swimming, so in this case to avoid drowning try to immediately seek an exit from the water.
Interestingly, even when all Emphasis drugs have been used (Normal status) and even with Herculean tonic and Energy Stimulant , it is not possible to escape Eden. No difference was noted in drowning times with or without enhancements over a dozen attempts.
Once cured, the player can swim forever without drowning or fatigue.