Exactly 215 years after revolutionary patriots dumped 342 chests of tea into Boston Harbor to protest colonial tyranny, an explorer launched an effort to retrieve them.

Barry Clifford, a salvage entrepreneur who located the first pirate ship in the New World four years ago, stood on the docks of Boston Harbor in below-freezing temperatures Friday, gesturing across a channel as divers prepared to jump into the icy waters."It was a cold night, the winds were coming from the northwest and the tide was coming in," said Clifford, referring to the evening of Dec. 16, 1773, when 30 patriots, angered over King George III's three-penny tax on a pound of tea, raided three ships and dumped the tea overboard.

Clifford hopes to bring back about 40 or 50 of the wooden chests and place them in a museum with some of the $40 million in artifacts he found on the wreck of the pirate ship Whydah in 1984.

He is not bothered by criticism that he may be disturbing historical sites or the skepticism voiced by museum officials about whether the tea chests are still intact after two centuries underwater.

"We've left this alone for more than 200 years," Clifford said. "Boston Harbor is one of the greatest archaeological resources we have. We've already gotten letters from schoolchildren around the country. It's good when something like this focuses attention on a historical event."

Though the actual site where the tea was dumped, Griffin's Wharf, now lies 150 yards inland under a Boston Edison substation, Clifford said he believes tides would have moved the chests into the Fort Point area. He said most of the crates were simple wooden boxes except for about 50 that were of an ornate Chinese design.

Using a chartered lobster boat, Clifford and a crew of five motored to the middle of Fort Point Channel, an area of the harbor located between downtown and South Boston.

Three divers wearing dry suits and thermal underwear prepared to dive 35 feet into the water searching for signs of the crates. Clifford also directed electronic searches of the area using sidescan sonar and sidebottom profiling machines.