The largest underwater waterfall in the world

The world’s biggest waterfall is underwater and nobody has ever looked at it. In the Denmark Strait, cold dense water from the Nordic seas pours over a ridge on the seabed and sinks about 3,500 m into the warmer Atlantic water below, at a rate NOAA puts at roughly 5 million cubic metres a second. It is a genuine waterfall of water, inside the ocean, and it shows up in instruments, not photographs.

The Mauritius one is the opposite in every respect except the name. It is sand and silt sliding off a shelf about 150 m deep into a drop-off of more than 4,000 m off Le Morne, and it looks like a waterfall only from a few hundred metres up because pale sand is streaming across the line where shallow water turns dark. It is small, it is an illusion, and you can go and look at it from a helicopter on a Tuesday. Search engines lump the two together; they share nothing but a phrase. See is the underwater waterfall real.

The same search tail asks if a person can survive going over a waterfall, or swim up one. No, and no. Nobody should jump, swim or boat over any waterfall, and neither of the two above is somewhere a person can be. If you want a waterfall you can stand at the foot of, Chamarel is about 100 m and on the helicopter loop; see Chamarel versus the underwater waterfall. If you want the illusion, it is on how to see the underwater waterfall.

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