It covers two-thirds of our planet -- and we've discovered just 5 percent of its secrets.

From Shark Week to a sandy fold-out chair on the beach, we’re no strangers to the ocean. Actually, that’s a lie. We know shockingly little about the deep blue considering how many centuries humanity has existed alongside it. We may think of space first, but make no mistake: we have our own frontier right here, and for the first time in all of human history we’re advanced enough to explore it in earnest.

What might be waiting for us?

A cure for cancer.

Meet the Rasta sponge. Aside from its day job of being a slimy blob, it's full of anticancer compounds.

And you thought it was just a pretty face!

It's one of an increasingly astonishing lineup. Scientists recently rediscovered a gray sea-sponge they'd lost track of in the gigantic ocean. “When bits of the sponge were first found in 1984," ABC News reports, "preliminary tests showed a chemical within it was about 400 times more potent than the drug currently used to treat breast cancer, Taxol." Scientists now have a chance to move forward with that discovery.

Then there's the more photogenic Mycale henscheli sponge -- a tongue-twister of a name. It has a track record of 90 percent tumor growth inhibition as of July 2015.

Along the rocky Irish coast, marine sponges are being studied for cancer and AIDS treatment.

The ocean -- or the 5 percent we’ve researched in the last few decades -- has given us tools to take down long-standing and debilitating diseases. What will we find in the overwhelming amount we have left to discover?

Crazy/weird marine life.

The ocean gets colder, darker and higher-pressure the deeper you go. The furthest reaches resemble the surface of an alien planet.

Marine environments are dazzlingly foreign to us, and the same goes for the creatures that live there. Built to thrive in bizarre environments, they take shapes and sizes that are beautiful, odd and downright terrifying. Jaws, dolphins and "Finding Nemo" may come to mind first, but consider these ...

Sea angels (aka adorable marine slugs).

Kelp Forests.

Mantis Shrimps who see 16 colors vs. our basic three and punch things with enough force to boil the water/cause shockwaves. Don't let anyone say you have to pick between being pretty and kicking butt, kids.

The Red Sea's glow-in-the-dark coral reef.

To date, we've discovered about 220,000 marine creatures. There may be as many as 2 million more. Sadly, many will go extinct before discovery due to pollution, rising sea temperatures and other factors.

Clean Energy.

Solar power relies on sunshine. Wind power needs a breeze. But waves? They never stop moving.

They generate energy as they slosh around in constant motion. That energy can be harnessed (if you're curious) and converted to electricity. For a little perspective, consider all the explosives detonated in World War II. That same amount of energy breaks on the world's coastlines every two hours or so. Capture it all and we could renewably power 5 million American households for an entire year.

The upshot.

Conservation, oil spills and the floating continent of garbage (really) aren't just topics of conversation. They're events with real and measurable damage, even if they're happening thousands of miles out at sea.

The ocean is one thing all humanity has in common as a food source, as a means of travel and connection, as a shared treasure and resource. Like space, it's one of our final frontiers: one of the last things on earth which can -- and should -- make us feel truly small. Its size is only rivaled by the potential we've discovered and the secrets that remain.

Let's protect them.