Lake Baikal sediment layer almost as deep as the Mariana Trench:

https://en.wikipedia.org/wiki/Lake_Baikal#Geography_and_hydr...

[...] and below this lies some 7 km (4.3 mi) of sediment, placing the rift floor some 8–11 km (5.0–6.8 mi) below the surface, the deepest continental rift on Earth.

Oh right. Basically China has its own tectonic plate, with Baikal on the rift, top left: https://en.wikipedia.org/wiki/Amur_plate I did not know that.