Question

it is easier to swim in sea water than on the pond why

Answer 1

because sea water is denser so we get more buyancy to swim
hope this will help u

Answer 2

It is easier to swim in sea water than fresh water because of its high density resulting out of salt content, Which won't drown you compared to fresh water. if the fresh water is not flowing and stagnant like a pond or a well, then it is easier to swim at sea.