Just keep swimming.
Freediving and snorkeling are two forms of exploring beneath the water without having a consistent air supply. They are both very different and require a different skill set. Freediving is the act of diving as deep as possible and back to the surface on a single breath. It is considered to be a true test of your ability to control your body.
Snorkeling is essentially the opposite of Freediving. You primarily float above the water or dive down to relatively shallow depths to look at marine life. Snorkeling is not meant to test your body, but merely to just enjoy your surroundings.
Freediving is primarily a solo sport while snorkeling is a group activity. While you can do both activities anywhere with water, snorkeling is most enjoyed in places with interesting sights and warmer water, like the Caribbean. Freediving also can be done anywhere, but unlike snorkeling, it is more of a group activity and nearly anyone can participate.