Sometimes they are zigzag lanes of water just wide enough to be impossible to cross.

Sometimes they are rivers of open water from half a mile to two miles in width, stretching east and west farther than the eye can see.
There are various ways of crossing the leads.

One can go to the right or the left, with the idea of finding some place where the opposite edges of the ice are near enough together so that our long sledges can be bridged across.

Or, if there are indications that the lead is closing, the traveler can wait until the ice comes quite together.

If it is very cold, one may wait until the ice has formed thick enough to bear the loaded sledges going at full speed.