One of the many courses we teach in Dive Operations to staff and volunteers is freediving. There's much more to it than just holding your breath for as long as you can. There are breathing techniques, positioning and form, and lots of practice.
The Georgia Aquarium dive team has a joint project out of Savannah, Georgia with NOAA, National Oceanic and Atmospheric Administration, in an effort to eradicate the non-native lionfish. Lionfish species (specifically the species Pterois volitans and to an extent Pterois miles) have invaded the Atlantic coasts of both the US and Central America.