I did some collecting in PR in September 1994. We stayed at a parador just
outside of Rincon on the west coast. There was a sandy beach right in front
of the place that extended as far as the eye could see on either side. I
understand the beaches are public property, so one could walk on them as far
as one wanted to. I collected a whole bunch of Donax, small key-hole limpets
and many other mostly small shells on the beach. I did some snorkeling. That
part of the island is not very rocky. There are only small groups of rocks
separated by sand. We also went to a place known as "The Shacks" or more
formally as Playa del Bajo, located to the west of the town of Isabela. It is
near the northwest corner (PR is more or less shaped like a rectangle). It is
a popular scuba diving location, because there are some shallow reefs close
to the shore. There were many gorgonians with live Cyphoma gibbosum on them.
I don't recall seeing any large shells.
 
The nice thing about PR is that almost everybody speaks, at least
understands, English. On the way out, travellers are required to declare
animal & plant matter they are carrying to USDA officers.
 
A.