Dream About Swimming Deep Water

i jumped into a pool, there were a couple people in it. For a while, i was swimming around the top and enjoying it until i swam to the bottom. I feel like i underestimated how deep I was swimming under the water because when i looked up the distance was farther than i remembered looking up. I didn’t panic, i just started tryin to swim to the top. But for some reason i couldn’t swim to the top without getting tired and sink a little closer to the bottom. i eventually let myself drop to the floor completely to take a break. and then i pushed myself off from the floor and swam all the way to the top with little effort. When i looked at the people around me no seemed to notice how long it took.