Gahan Hammer, a Washington actor who has given up the stage for underwater pursuits, was trudging through the deep snow with an aqualng on his back, singing a Theodore Bikel-like minor-key dirge:

See the crazy divers

Tramping through the snow,

Chopping through the thick ice,

What a way to go!

As he shouted the last he lost his footing and came tumbling down the steep hillside, stopping just where the cliff fell away into a dark and forbidding abandoned limestone quarry.

The laughing Hammer and four other divers of questionable common sense were in Martinsburg, W. Va., last weekend to explore the 70 feet of water that lay beneath the ice in the quarry. Their mentor was Tom Cooper, who runs the National Diving Center on Wisconsin Avenue and who says of ice diving:

"We're divers. That's what we like to do. And in the winter, when the places we like to dive in get covered by ice, we have two choices. We can either go somewhere else, which we do sometimes, or we can cut a hole through the ice and dive there."

According to Cooper, divers fancy themselves explores. Explorers don't always go to pretty or convenient places. Sometimes they go to hard, ugly places just to be able to say the've been there.

Like iced-over limestone quarries in Martinsburg, W. Va.

It took two days of planning for the divers to set up this trip. They met Saturday morning at a fast-food joint in Martinsburg. Over soggy egg sandwiches, Cooper constructed a waiver and had each diver sign it. If they didn't come up it was to be no fault of the old-timer who owned the quarry.

Cooper with great fanfare presented each man a Hershey bar, to be consumed just before entering the frozen water. Then he gave the marching orders.

Hammer would be safety man, controlling a 300-foot yellow nylon line at the hole in the ice. The four divers would hang on to the line as long as they were under. One tug from the divers meant "give more line," two tugs meant "we're stopping," and three tugs, said Cooper, "means 'get us the hell out of here,'"

Should the line go slack, indicating that somehow the divers had lost it, Hammer was to dive in, follow it to the end, then take 50 more feet and do a complete circle until he found them.

Without the rope the divers would be utterly and hopelessly lost. Cooper said the odds against finding a three-foot-square hole somewhere in acres of ice were immensely unfavorable.

Instructions over, the divers piled into cars and trucks and made off across back roads to the quarry, where great sheets of sheer-faced rock dipped 70 feet to the hard, flat surface of the ice.

There they climbed, one by one, into the heated rear of Copper's camper-truck, where they slipped out of parkas and boot and into pantyhose, rubber wetsuits, booties and gloves and greased their faces and squeezed on full hoods of rubber and nylon that scrunched their faces into grimaces.

Then it was off across the snow the half-mile down an abandoned road to ice's edge, where a brook trickled into the quarry through a small break in the hard surface.

Cooper smacked open a three-foot hole as the troops marched down the hillside. Then each stepped gingerly into the frozen water, howling in shock as the bitter liquid seeped into the suits and they waited for body heat to warm them up.

Soon there were four figures bobbing in the icy water, snorting and snuffling. The safety line was paid out and with a silent flip Cooper upended himself and slid off under the ledge. David Ifshin, who had earned his scuba certification only a few weeks before, followed. Then came Kevin Baker, wearing a ridiculous Woody Allen-style blowup drysuit contraption. Last was the youthful John Davis of Potomac.

There was a brutal deathly silence when Davis disappeared. Hanmer dealt out line on call. "Weird," he said, "this feels really weird."

And then, seemed almost instantly, they were all back, yipping and shouting and crashing up onto the shore. In fact, it had taken 18 minutes and now it was over. Two days of planning, thousands of dollars' worth of equipment, months of training and a substantial degree of danger. For what?

"Well," said Ifshin, "there really wasn't much to see. It's sort of like sking in the East. It's dark and gray and not particularly pretty, but you do it because you love to ski and that's all there is."

And everybody raced back to the truck, laughing and running, climbed out of the frozen suits and thundered off to a pizza place, where they ate and drank and talked about what a great time they'd had.

Weird. Really weird . . .