Read the wiki article above, it has links to other articles where it’s sourcing its information.
Link to article documenting his expedition across the frozen Bering Strait.

“Karl Bushby reached land after 14 days walking across shifting plates of ice in temperatures reaching -30C.” “The ice was breaking up behind him as he walked across.”

However, it does appear that some of his walking has been replaced by swimming.
“In August 2024, Bushby started the swim across the Caspian Sea from Kazakhstan, planning to finish in Azerbaijan to avoid going through Iran or Russia, as both countries were then too dangerous to enter with a British passport. Bushby was accompanied by co-swimmer Angela Maxwell and two Azerbaijani national swimmers, Anastasiya Boborikna and Abdurrahman Rustamov.[15] Each day, Bushby and company swam in two 3-hour sessions: one in the morning, one in the afternoon and resting and sleeping on support boats each night.[16] The swim covering 179 miles (288 km) was achieved in 31 days with 132 swimming hours.[17][18] From Azerbaijan, Bushby then went to Turkey to cross the Bosphorus Strait into Europe”

He’ll probably end up swimming across the English channel.