There's all sorts going on in that world beneath the waves and a couple of fishing Floridians decided to take a look at what was below their boat by dropping their GoPro down.
It's become a popular way of capturing marine life in its natural habit as undisturbed by humans as possible, instead of sending a person down with a camera you can just drop the camera down.
It helps that fish tend to be an inquisitive bunch and will often swim right up for a convenient close-up, while there's so often a shark lurking around in the background.
When couple Jay and Elizabeth decided to drop their own GoPro into the water and see what manner of aquatic animal was directly below their boat.
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What they found, as one so often does in the sea, was plenty of fish along with a shark having a bit of a swim in the waters so it's just as well they sent the camera down instead of going for a quick dip themselves.
Some might find it scary that just the thin hull of a boat keeps someone separated from the water that would sink their vessel and all manner of creatures that would possibly not appreciate a landlubber disrupting them.
Fortunately in this case, the shark seemed fairly unbothered about chasing after all of the fish around it, and indeed sharks will often ignore fish in their area because the little swimmers are actually cleaning them.
Plus they'd rather save their energy to go after bigger targets, which often doesn't include humans as despite their reputation for being fierce chompers, sharks very rarely go after us.
It's still not a gamble you'd be wise to keep making, and even if they don't eat you they might give you the scare of your life as happened to one diver who had a close encounter with a great white shark that drew some clear screams from the man.
In this case the scenes the couple captured beneath their boat were fairly tranquil, just an underwater world with fish going about their business.
Other GoPro footage from the sea has helped shine a light on some of the damage we're doing to the environment, as other people filming have found heaps of rubbish dropped by humanity.
While the Florida couple got some fun footage, others have shown the piles of plastic, sometimes including entire garden chairs, that have been ditched into the water.
One step up from lowering your GoPro down into the water on a line is giving it to a sea creature to do the filming for you.
A team of scientists fitted a turtle with a camera to look at the Great Barrier Reef and got a good look at the sad truth that much of this incredible feature of nature was dying.
Joe Harker