I think it's flotation.
Michael Phelps
There are many records for swimming. This is because there are many different swimming strokes. They were also set at different times.
when you are in a pool you are less dense and are lighter
Michael Phelps of USA (For swimming).
Michael Phelps currently holds the world record for winning the most swimming medals. He has won 14 gold medals from swimming during the 2004 and 2008 Olympic games.
Michael Phelps
michael phelps
Not many, a average swimming pool holds approx, 12, 000 to 15,000 gallons of water.
Michael philps
39,636 pounds
Missy Franklin holds 11 world records in swimming.
Michael Phelps, who did it all during the last summer Olympics