Here's the little pool at Mango Marina.  Most of these marinas are inexpensive places to tie up.  They all have nice grounds, restaurants- or at least a barbeque- and plenty of spots to lounge about.  One has a store, another its own rubber plantation.  Some of them have guest cottages, mostly for Guatemalan weekenders.  They're all within a 15 minute boat ride of the town of Rio Dulce, that chaotic marketplace for all necessities.