There was a subsea survey a decade ago that extrapolated out to three million* of the damn things.
We're only now looking at the mud volcanoes in the Arctic.
Lots of stuff to figure out.
From Nautil.us Oceans:
Scientists don’t even know how many seamounts there are—but the few they’ve explored are extraordinary.
There are mountains in the sea.
From tens of thousands of extinct volcanoes rising thousands of meters from the ocean floor, to hundreds of thousands or even millions of smaller knolls, hills and ridges, seamounts are abundant features of the world’s ocean.
That these numbers are so unsettled speaks to just how much remains to be learned about seamounts. Yet the small fraction that have been studied suggest they are extraordinary places, teeming with life, swirling with energy.
Seamounts are formed where Earth’s crust and upper mantle is active at the bottom of the deep sea: at the boundaries of shifting and spreading tectonic plates, near volcanic island chains and archipelagos. Some seamounts have the conical shape of extinct volcanoes, though most have eroded over time, their mountainsides slumped, debris tumbling into the abyss.
....MUCH MORE
Formed by magma eruptions and lava flows that calmed and cooled into rocky basalt crags, metallic crusts, and volcanic sand, seamounts are hard, vertical structures in an otherwise soft and horizontal deep sea bed. They present a surface where suspension-feeding invertebrates can settle and grow. Sponges and cold-water corals in a kaleidoscope of shapes—bugles, fans, pens, spirals, pillars, domes—are visited and tended by sea stars, sea lilies, sea spiders, urchins, anemones, octopus, spiny lobsters, and fish.
Seamounts are associated with more than 1,300 different species of animals. Some are unique to seamount habitats. A few, such as the spiny lobster Jasus caveorum of the Foundation Seamounts in the southeastern Pacific Ocean, or Gnathophis codoniphorus, a conger eel found on the Great Meteor seamount in the Northeast Atlantic, live nowhere else but a single seamount. These are creatures most beautiful and bizarre, striped, spotted, fang-toothed and jut-jawed, fringed, finned, tentacled, tendrilled.
All are fed by the seamount itself, which intercepts currents and tides and enhances the flow of food and nutrients falling from above or welling up from below. The creatures of the seamount change with depth, from a summit that may be in the sunlit zone, swirling with schooling fish, down through layers of scattered light, to the darkness thousands of meters below. Some shrimp, crabs, and tube worms spend their entire lives in the murky mineral plumes of hydrothermal vents....
*Weird Hum Heard Around the World Was the Birth Of A Submarine Volcano
Here's a 2007 story from NewScientist:
The true extent to which the ocean bed is dotted with volcanoes has been revealed by researchers who have counted 201,055 underwater cones. This is over 10 times more than have been found before.Human beings aren't near as smart as we think we are, a point I exemplify on a daily basis at Climateer Investing.
The team estimates that in total there could be about 3 million submarine volcanoes, 39,000 of which rise more than 1000 metres over the sea bed....
