sinkholes

The Well of Barhout (also nicknamed Well of Hell) is a sink hole in Al-Mahara, Yemen. It is about 30 m (100 ft) wide at the surface, and 112 metres (367 ft) deep. ... https://en.wikipedia.org/wiki/Well_of_Barhout SOURCE...

I didn't find a whirlpool thread, but I guess this is probably a sinkhole that opened under the water.

Reading the thread on humans buried in concrete reminded me of a story I heard when I was a kid. I lived on a crossroads and I was told by several people that in the early years of the 20th century a house and cart had just turned one of the corners when the ground just opened up beneath them...