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Where badass fish climb rock cliffs... with their mouths

Some of the world's toughest rock climbers live on Hawaii's Big Island, where they scale sheer rock the equivalent of a 26-mile vertical marathon.

Think you're tough? Try climbing this... without any arms or legs.
Eric Mack/CNET

HONOMU, Hawaii -- The volcanic hills and ridges above the Hamakua Coast on the Big Island of Hawaii are among the wettest places on the planet. Naturally, all that water forms plenty of spectacular waterfalls and streams, and naturally, you can find a variety of fish in these waters as they rush toward the Pacific. So, it's also only natural to assume that some of these fish can be found climbing the vertical cliffs behind the waterfalls to get closer to the source of all that water.

It sounds like a story from the mind of my 6-year-old daughter or a sci-fi author who conjures images of militarized robot fish on covert missions in the tropics, but it turns out to be science fact.

I first learned about these rather remarkable species of goby during a visit to Hawaii's 422-foot tall Akaka Falls last month. There, the o'opu alama'o, also known by its scientific name lentipes concolor, begins life when it hatches from eggs laid in the waters above the falls. These embryo drift all the way down to the Pacific Ocean, where they remain and grow for a few months until they are ready to begin swimming back up freshwater streams toward the falls. Once they reach the base of the falls, they climb up the sheer, wet rock wall using a specially adapted sucker on their underside.

But this fish is actually not the strangest aquatic rock climber on the island. Another ambitious goby, the o'opu nopili or Nopoli rock-climbing goby (sicyopterus stimpsoni), frequents other nearby waterfalls on the Hamakua Coast. It makes a shorter climb (which is still more than 300 vertical feet) using its mouth.

"For a human to go the equivalent distance based on body size, it'd be like doing a marathon, some 26 miles long, except climbing up a vertical cliff-face against rushing water," researcher Richard Blob, an evolutionary biomechanist at Clemson University in South Carolina, told LiveScience.

While I unfortunately was unable to safely approach the particular waterfalls I visited to see the fish for myself, Blob and other researchers recently presented their findings that the Nopoli uses the same muscles for climbing as for eating and published it in the open journal Plos One. Scientists now hope to learn more about how the rock-climbing behavior of certain Hawaiian gobies evolved by looking at similar species that can be found on a number of other islands, including in the Caribbean.

My hope is that they find enough of these insanely tough fish in different nations around the world that we can hold a sort of Olympics for the world's finest finned athletes concurrent to the next summer games in Brazil. But perhaps I set the bar too high; I'd settle for a new inter-species event in the X Games: hard-core man vs. fish waterfall climbing.

Check out a captured Nopoli in action in the video below and hope that one of these guys never mistakes your leg for a rocky cliff.