CONCORD, N.H. (AP) – Northern New England safety officials want snowmobilers to use caution when crossing over ice, or avoid doing so altogether, after incidents in New Hampshire and Maine this weekend left one rider dead and landed six others in the water.

In New Hampshire, three snowmobilers went through the ice on Lake Winnipesaukee. Divers recovered the body of one of the riders, James Couet of Lowell, Mass., Sunday. In Maine, four people escaped injury on Sunday when their snowmobiles fell through the ice on two lakes.

Officials said riders should be particularly careful as temperatures grow higher toward the end of the week, but that even warm weather doesn’t make such episodes especially unusual.

“Sadly, it’s not exceptional,” said Bob Meyers, executive director of the Maine Snowmobile Association. “There’s always people out there who think they know best … It’s foolish.”

The New Hampshire Bureau of Trails, part of the state Parks and Recreation Division, has a clear message for riders: Stay off lakes. The warning is highlighted on the bureau’s Web site, www.nhtrails.org.

“Unsafe ice isn’t much of an option. It doesn’t give you much of a chance to plan for other things,” said Paul Gray, chief of the trails bureau.

Where necessary – including around the part of Lake Winnipesaukee where Couet fell through – local snowmobiling clubs maintain alternative land routes so that riders can avoid crossing ice, Gray said.

But he said the decision to ride over ice ultimately is up to the individual snowmobiler.

“All you can do is lead the people to the trough,” Gray said. “If they take a drink it’s up to them.”

Mark Latti, spokesman for the Maine Department of Inland Fisheries and Wildlife, said several snowmobiles have crashed through the ice since the start of the year, particularly on large lakes where ice conditions can vary.

“What we’re finding is that with the fluctuating temperatures that we’ve had, the larger lakes are unpredictable,” he said.

Recent snowfalls also have made lakes risky because the snow makes it hard to gauge the thickness of the ice, Maine wardens say. They say ice often is weak near points of land, rocky shoals and around islands.

Ice conditions in Vermont also can fluctuate by locale, said state police Lt. James Colgan.

“You may find good safe ice in the northern part of the state, but in the southern part there’s very little snow and ice cover,” said Colgan, recreation enforcement coordinator for the state police. “It’s a tough one to call.”

Sometimes the ice may appear safer than it really is, said Colgan.

“Even though they may say it’s good ice, it may be different,” he said.

Earlier this month two Quebec men drowned in Lake Champlain when their snowmobile fell through the ice near the Vermont-New York border. And during the weekend emergency crews rescued a man whose all-terrain vehicle had broken through the ice near St. Albans, Vt., said Brad Hanson, executive petty officer at the U.S. Coast Guard station in Burlington, Vt.