Couple of papers from the Italian team that did bathymetry / seismics in Lake Cheko:

http://sci-hub.cc/10.1007/s12210-015-0403-8

https://www.researchgate.net/publication/229759371_Lake_Chek...

Some argument against Cheko being an impact crater, referenced in the above work:

http://www.univie.ac.at/geochemistry/koeberl/publikation_lis...

Data from the Italian team that investigated Cheko:

http://www-th.bo.infn.it/tunguska/