https://en.wikipedia.org/wiki/Flying_fish
The Exocoetidae are a family of marine ray-finned fish in the order Beloniformes, known colloquially as flying fish or flying cod. About 64 species are grouped in seven genera. While they cannot fly in the same way a bird does, flying fish can make powerful, self-propelled leaps out of the water where their long wing-like fins enable gliding for considerable distances above the water’s surface. The main reason for this behavior is thought to be to escape from underwater predators,[3][4][5] which include swordfish, mackerel, tuna, and marlin, among others,[6] though their periods of flight expose them to attack by avian predators such as frigate birds.
I've never seen one up close before, it's interesting how much their fins look like feathers, though it shouldn't be that surprising given their purpose.