Despite the fact that a ferry could potentially cross from the USA to Siberia in two hours, political hurdles restrict traffic across this body of water.  It is virtually impossible for a westerner to receive permission to arrive on the Russian shores of the Bering Strait.  An adventurer wishing to kayak, swim, walk over the ice, or sail from Alaska to Siberia across the Bering Strait would have to do so illegally. 

Rentable bike cases.