system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do sharks and other marine life leap out of the water and isn't it a waste of energy to leap out that high?

I have seen many videos where a shark will leap more then two meters (about 7 feet?) out of the water then then just fall right back in. Recently I saw a video of an orca leap out about 4 meters out of the water. 

Why do they do this? Doesn't it waste energy to have to speed up so much in ordee to leap out that high?
gpt
Sometimes whales do it just for fun. They also seem to do it as part of their mating displays.

Leaping out of the water like crazy is a good demonstration of fitness. If the male whale can jump really high, it proves he's strong and fast, therefore his offspring will be strong and fast.

Fish jump out of the water to avoid predators. Even hopping up for a few seconds, away from whatever's chasing you, might be enough to save your ass. Flying fish, of course, are the craziest version of this.