New summer visitors: Gray seals thrive off Old Cape Cod.(Chicago Tribune)

CHATHAM, Mass. _ These days, on Old Cape Cod, it's even hotter than the sands. It's ecotourism, a way to move beyond beach parties, clam bakes, lobster boils and fudge shops. Following in the steps of Henry David Thoreau, who once spent three weeks walking the Cape to its tip, ecotourists are out spotting birds, exploring ocean inlets by kayak, striding along woodsy paths _ and watching seals off this charming port town on the Cape's southeast tip.

Nobody knows exactly why, but a decade ago gray seals started to summer off Chatham. They come in late spring, about the same time of the year as the first of the off-Cape hordes for whom the Cape had been a favorite vacation spot since the days when whaling captains called it home between trips in ships to the South Seas.

Each year, more seals have arrived. Now, at times, hundreds can be seen at once, basking on remote beaches, swimming and schmoozing with each other in a …