Two pilots in a helium balloon have completed their trans-Pacific flight with a sea landing after a six-day trip they claim breaks the world distance and duration records.

Troy Bradley and Leonid Tiukhtyaev landed safely 6.5km off the coast of Baja California in Mexico after a change in winds made a landing at sea a “more prudent” option than landing onshore.

The Two Eagles Balloon Team set off from Saga, Japan. Photo: AAP

The American and Russian duo flew for more than 160 hours and travelled more than 10,000km.

“Mexican authorities are cooperating fully and the Coast Guard is en route to the balloon. We anticipate they will tow the capsule to shore,” a statement from the Two Eagles team said.

The statement emphasised that the watery landing would not impact the validity of the balloonists’ record attempt.

“A water landing is acceptable under the international rules governing the establishment of world records,” the statement said, noting that two recognised around-the-world records also ended at sea.

The voyage, which began in Japan, had already surpassed the previous records for the longest distance covered in a gas-filled balloon, 8,467 kilometres and the previous duration record of 137 hours, five minutes and 50 seconds.

Mr Bradley and Mr Tiukhtyaev’s odyssey was eventually timed at 160 hours and 37 minutes at a distance of 10,696 kilometres, according to the Two Eagles team.

Filled with 10,000 cubic metres of helium and capable of staying aloft for 10 days, Two Eagles departed Saturday from Saga, southern Japan, and sailed over Tokyo at night before heading out across the wide Pacific.

The pair had planned to land in the vicinity of the Canada-US border, but set course for Baja California instead to avoid a ridge of high pressure off the US west coast.

The duo were the first to attempt a trans-Pacific balloon crossing since 1981.

The previous record for the longest distance ever travelled in a balloon was set in 1981 by Double Eagle V, the first gas-filled balloon to cross the Pacific Ocean from Nagashima, Japan to north-western California.

The duration record was established three years earlier when Double Eagle II became the first balloon to traverse the Atlantic, from the north-eastern US state of Maine to a farmer’s field outside Paris.

Two Eagles was named in honour of those two craft.

The unpressurised, 100 kilogram Kevlar and carbon-fibre capsule is described by the expedition as smaller than a king-sized bed, with freeze-dried food sharing space with state-of-the-art electronics.

The pilots had controlled altitude using some 4500kg of sand hung outside the capsule as balance, allowing the two men to vary altitude between 12,000 and 30,000 feet.

-ABC/AAP