If you're scuba diving in the ocean and come across a mysterious, giant floating mass...
Try not to panic.
It's just an Ocean Sunfish.
Yes, they're gigantic, with some weighing as much as 5,000 pounds and growing up to 9 feet long, but they don't snack on humans.
According to OceanSunfish.org, their diets mainly consist of, "zooplankton like jellyfish, Portuguese man-o-war... squid, sponges," and other small fish.
While the Sunfish does make the diver next to him look like a puny bug, he is actually pretty friendly.
As the divers swim up to him, the Sunfish seems to be relishing in his 15 minutes of fame, posing for a number of pictures.