A surge in Arctic tourism is bringing ever-bigger cruise ships to the formerly isolated, ice-bound region, prompting calls for a clamp-down to prevent Titanic-style accidents and the pollution of fragile ecosystems. Arctic nations should consider limiting the size of vessels and ban the use of heavy fuel oil in the region, industry players said after the first luxury cruise ship sailed safely through Canada's Northwest Passage this summer.The route, which connects the Atlantic and Pacific oceans via the Arctic, was once clogged with icebergs but is now ice-free in summer due to global warming.With a ticket price of $19755, the 1700 passengers and crew followed - in reverse - the route first navigated more than a century ago by Norwegian explorer Roald Amundsen. They left Anchorage in Alaska on August 15 and docked in New York on September 16.The ship's operator, Crystal Cruises, says on its website it will repeat the voyage next year.Two shipping executives expressed concern the one-off trip could become a trend, citing worries over safety, risks to the environment and the impact on small communities, in an area where there is no port between Anchorage and Nuuk, in Greenland."The Northwest Passage is thousands and thousands of nautical miles with absolutely nothing ... There is a need to discuss regulation," said Tero Vauraste, the CEO of Arctia, a Finnish shipping firm specialising in icebreakers.Were a ship to be in trouble, there would be little authorities could do given the lack of infrastructure.Another concern is environmental. "Potentially, an accident involving a mega-ship could represent an environmental disaster," said Daniel Skjeldam, CEO of Hurtigruten, a cruise ship operator .The Crystal Serenity did not use heavy oil during its trip, its operator has said."Heavy oil in cold conditions is sticky and takes much longer time to break down so it has a prolonged effect on the environment," said Marco Lambertini, director-general of World Wildlife Fund International. ..