I recently ate two varieties of crustaceans from there.
The first is the true blue local crab, which is hairier than usual. It's shell is also tougher than what we from Manila (who are used to eating at Dampa or Seaside) are used to. And they're average-sized. They are also harder to eat, not only because of the tougher shell you have to crack but also because the hard plates and projections in the crab's stomach (under the gills) are too narrow (and also tough). But they're delightful to be eaten just the same.
Last Holy Week, they were being sold for about P90/kilo (yes, so cheap!). Note however that this may be a seasonal fare. They may also be cheaper at other times when seafood isn't in high demand so make sure you haggle nice.
The other kind of crustacean I had the wonderful opportunity to try was locally referred to as TIPAS. These are small crabs caught on beach shores. Usually, one can just lure them with fish in hand. I think, upon smelling the dead fish, they'd let the waves carry them to you (or they'd go out of their burrows).
fresh tipas collected in a bamboo pole at the beach
You just really wash them well and then deep fry. Serve with vinegar spiced with garlic and salt. They taste just like your usual crispy crablets (but of course, they have that extra zest of freshness).
I believe there is another kind of crab that people in Marinduque can enjoy. It's usually ordered already cooked and wrapped in banana leaves. I just forgot what it's called and have yet to sample it.