Citing rough conditions, searchers on Saturday called off the sea hunt for missing water-sports instructor Nathan Clarke, while a sunset alarm proved fruitless as divers answered reports of an object snagged on a reef outcropping.

Towed 450 feet offshore by paddleboard, police divers working alongside an emergency vessel unsuccessfully scoured a broad area of reef running parallel to Public Beach, but were unable to find a patch of waterborne material reported by a helicopter crew.

Mr Clarke, 31, missing since Saturday 25 February, was last seen in the early evening at the water’s edge, wearing beige shorts. A bather found his cell phone, however, on Wednesday, 29 February, in 10 feet of water, approximately 150 feet offshore. His wallet and sunglasses have not been located.

The family of the part-time teacher arrived in Grand Cayman on Saturday evening, joining the parents of fiancée, Lisa Beck, 32, who arrived earlier in the week to aid the search. The couple has lived in Cayman for four years.

On Saturday, 3 March, police continued to interview visitors and Public Beach regulars, seeking clues to the whereabouts of Mr Clarke, as his family arrived from Europe in the evening.

The sunset survey of the reef, cut short by darkness, resumed at first light on Sunday, but turned up nothing. Chief Inspector Richard Barrow, West Bay Area Commander, said the general sea and land hunt would start again at 8:30am.

“It’s been a week now, and we will comb tomorrow until we have exhausted and explored every possible avenue,” he said, describing ongoing efforts to find the missing man.

“We have used marine assets, hundreds of volunteers, fixed-wing aircraft and divers, but Mr Clarke has not been found,” he said.

He paid tribute to the efforts of the searchers, citing more than 28,000 hours expended throughout last week by nearly 530 volunteers and 39 police officers. He vowed to continue the land-side hunt of nearby dykes and abandoned buildings, although the cell-phone discovery had shifted the focus from the surrounding bush.

Officers had remained on site until as late as midnight during the week, Mr Barrow said, “revisiting the scene with a view to jog people’s minds, their memories, offering hand-outs and flyers, and surveying people.

“We want to enable access to information for people, and also give those people a chance who might be able to give us information,” he said.

Mr Barrow declined to speculate on Mr Clarke’s fate, moving only to dismiss rumours of criminal activity. “He had to have lost it,” he said of Mr Clarke’s cell phone. “It was not thrown” into the water.

Asked about possible drowning and why prevailing currents had not washed objects ashore, Mr Barrow said it was impossible to predict.

“It depends on the time of year, on the climate, how long something may have been gone, I really couldn’t say.”

Directions to divers had ensured a comprehensive survey of the area, he said.

“We search on a grid pattern so we know exactly what has been covered, that there is no overlapping and we do not miss anything. The volunteers throughout the week have been overwhelming,” he said.

Volunteers, friends and family attended a Sunday-evening candlelight vigil for Mr Clarke, as police gathered under a nearby tent with both families, planning strategy for the coming week. The search is set to resume this morning. Police have not said how long their efforts will continue.