You Are Still Sweating
Swimmers in cool open water don't feel like they're sweating, but the metabolic heat of swimming hard means sweat losses do occur - they're just masked by the water on the skin. Research on competitive swimmers has measured meaningful sweat-rate values during long-course training and racing.
The Practical Implications
For sessions under an hour, water before and after covers it. For ocean swims of 2+ hours, masters swimming events, or open-water races, in-session fluid matters. A bottle on the boat or at the feed station, with an electrolyte mix or sports drink, is standard.
Feed Station Approach
Marathon swim events typically use feed sticks - a bottle attached to a pole that's handed out to the swimmer mid-effort. Swimmers grab and sip in 5-10 seconds without breaking stroke much. The drink is usually an isotonic sports drink (Gatorade, Powerade, custom team mixes) with some carbohydrate for fuel alongside electrolytes.
Salt Water and Swallowing
Long open-water swims involve some unintentional saltwater ingestion. This isn't dangerous in moderate quantities but it can contribute to nausea and to the general feeling of being a bit unwell. Sipping fresh water from the feed bottle helps.
Post-Swim
The post-session window is straightforward - sodium-containing fluid plus food. For long sessions in cold water, a warm electrolyte drink (a tablet in warm water) is a small luxury that goes down well.
Frequently Asked
Do swimmers get dehydrated?
Yes - swimming generates metabolic heat that the body sheds into the water, with measurable sweat losses during long sessions. The feeling is masked by the surrounding water.
What do marathon swimmers drink?
Most marathon swim events use feed sticks (bottles on poles) handed to the swimmer mid-session. Drinks are usually sports drinks with carbohydrate plus electrolytes.
Should I drink electrolytes after open-water swimming?
For sessions over 90 minutes, yes - a sodium-containing drink helps replace what was lost. For short pool sessions, water plus normal eating is fine.
