Swimming is a wilderness skill. When swimming you can swim for only a little while before your legs get tired and you drown. You can swim in all compass directions, plus up and down. When you swim down you go under the water and you will need to hold your breath. Swimming up is only if you are under water and in need of air. If you are not good at swimming then you will swim more slowly and be more likely to accidentally swallow some water.
See also: wilderness, breathe, hold breath