1. To swim from location or one body of water into another. We squeezed through a crack in the wall of the underwater cave and were able to swim into a tiny moonlight chamber. Don't go too far out—the tide will make it very hard to swim back into shore. Please swim into the shallow end. It makes me nervous when you're in the deeper water like that.

2. To swim in the opposite direction of some force, such as a tide, current, wave, etc. The worst part of the triathlon was the swimming, because we had to swim into the current nearly the whole way. You'll have to swim into the smaller waves with your board to get to the part of the water where the waves are big enough to lift you up onto the surfboard.