Kohler has explored shipwrecks around the world, including the SS Andrea Doria and the RMS Titanic. Diving from the Russian research vessel Keldysh, Kohler made multiple dives to 3,786 meters (12,421 ft) in the MIRsubmersibles to explore the Titanic's wreck site.
Kohler was part of a team led by oceanographer Robert Ballard which explored and mapped the wreck of the U-166 in the summer of 2014 with remotely operated vehicles and determined that the bow of the submarine was destroyed, apparently by a depth charge which caused an internal explosion of the submarine's own torpedoes.[3]