Maine Warden Service via AP

This undated photo released by the Maine Warden Service shows Nicholas Joy, 17, of Medford, Mass.

A teenage skier who went missing two days ago on Maine's Sugarloaf Mountain sheltered himself from the elements by building a snow cave, authorities said. He was found Tuesday morning by a snowmobiling firefighter, cold and wet, but otherwise in good condition.

Nicholas Joy, a 17-year-old from Medford, Mass., was reported missing by his father at about 1 p.m. Sunday after the two became separated while skiing at Sugarloaf ski resort, said John McDonald, a public information officer with the Maine Warden Service.

Temperatures in the area have been in the low- to mid-30s the past two days, with a wind chill in the 20s. At one point during the search for Joy, visibility on the mountain went down to zero, authorities said. 

A Massachusetts firefighter who had heard that the teen was missing decided to search for him by snowmobile, NBC affiliate WHDH.com reported. The firefighter, who is familiar with the area, came across Joy on the Caribou Pond Road ski trail, about four miles away from the resort.

In a news conference Tuesday, Lt. Kevin Adam with the Maine Warden Service described how Joy instinctively went into survival mode once he realized he was lost on Sunday, building the snow cave as night fell.

"The next day, which would have been Monday, he did some going away from the snow cave, trying to find his way around," Adam said. Joy heard snowmobiles far off in the distance -- which Adam said were searchers looking for him -- but instead of attempting to venture that far in the cold weather, he retreated to his snow cave for another night.

"Then this morning, [he] was going in the direction of the snowmobile trails when he actually came across the snowshoe trails from the people who were looking for him. He followed those out to the snowmobile trail, started walking down that about a mile and a half before he was picked up by the snowmobiler," Adam said.

Joy kept hydrated over the past two days by drinking water from a nearby stream. Authorities still need to talk to him more to figure out how he got lost in the first place while skiing.

"Obviously, he made some errors getting off the trail, but he used his head and he made some very good decisions in building a snow cave. Even staying with the snow cave was a good decision," Adam said. 

The high school senior was reunited with his family in the ambulance, which he hopped into with only a little assistance from emergency personnel as news cameras rolled.

"He's in good condition," McDonald said. "He has been taken to the hospital just to be evaluated for possible hypothermia."

Eating a granola bar and drinking a bottle of water handed to him by one of the members of the rescue team before he got into the ambulance, Joy told WHDH.com, "I'm OK. I got lost."

This story was originally published on Tue Mar 5, 2013 10:24 AM EST