Tagus Cove and the Bolivar Channel are the coldest, most productive waters in the Galapagos, the upwelling of the rich Cromwell current makes for frequent sightings of dolphins and whales in the area. Tagus Cove, named for a British naval vessel that moored here in 1814, was used historically as an anchorage for pirates and whalers.   The cove's quiet waters make for an ideal dinghy ride beneath its sheltered cliffs, where blue-footed boobies, brown noddies and pelicans nests. Flightless cormorants and penguins inhabit the lava ledges near the ocean.