What is the identity of the huge hole on the Martian surface visible on Google Mars?

A mysterious huge "deep hole" has been found that the diameter is over 100 meters on the surface of Mars and the bottom is black and nothing can be seen because nothing can be seen. In fact, what is this?

Its identity is as follows.
SPACE.com - Deep Hole Found on Mars

Technobahn News: The entrance to the underground world, a mysterious black circle found on Mars

Several other holes have been found. The diameter ranges from 100 meters to 250 meters.

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It is over 100 meters.

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It seems that this is actually a "valley" rather than a hole, on geographical classification. There is something similar on the planet. The following is a similar example.

Cave of the Swallows


It is quite amazing ...

· Omaque:It might be like this.