Though I have never cruised the western Caribbean, I have a friend that has a house in Cahuita, South of Limon, and I have spend some time along the region. There really isn't any ports
except at Limon and that one is primarily a commercial
port that does not have any anchorages
. The rest of the coast is not accessable at all unless you have a really calm day and anchor
out in the Caribbean, but you will not have any protection at all. Puerto Viejo is a neat hippie town that has some nice restaurants, same could be said for Cahuita. Limon is a larger city(town) that has banks and better markets. There's not much to the North except Tortuguero Park and you may need a permit
to enter during turtle nesting periods.
My advice is to stick with Panama
, rent a car for a day or two and travel into Costa Rica that way.