I'm contemplating a circumnavigation by land and sea only (no planes) and plan to use cargo ships to cross the Atlantic and Pacific. So far it looks like the bi

I'm contemplating a circumnavigation by land and sea only (no planes) and plan to use cargo ships to cross the Atlantic and Pacific. So far it looks like the biggest hurdles are planning the trip around cargo ships. From what I've read, the passenger accommodations are booked far in advance and ships don't necessarily leave on a set schedule.There is usually a window of +/- several days, with possible delays that could last much longer.