Definition of "crossable"

Once the wet kicks in up north, you can be stranded for months waiting for swollen rivers to subside to a crossable depth, but visiting Cape York at this time of year was unavoidable for me, as the wet season is the only time of year that the Red-bellied Pitta and Black-winged Monarch are present, spending the rest of their time in New Guinea.

2005, Sean Dooley, The Big Twitch, Sydney: Allen and Unwin, page 289