The ferry dock in Skagway sank this morning for reasons unknown to Alaska state officials.

Ferry service to Skagway from Juneau and Haines has been suspended until further notice.

Skagway-bound passengers scheduled to sail Friday from Juneau aboard the Alaska ferry LeConte were notified this morning that the ferry will be turning around in Haines.

Engineers with the Alaska Department of Transportation were scheduled to fly in this morning from Juneau, and a diver was standing by for their arrival, department spokesman Jeremy Woodrow told the Star today.

Woodrow said the department is hoping to know more this afternoon, once the diver has had a chance to inspect the sunken dock, under the supervision of the engineers.

There is nothing to suggest there was anything suspicous about the failure of the concrete structure, he said.

"We do not have a lot of information about why this happened, or the cause,” Woodrow said.

"We have two marine engineers flying up from Juneau right now.”

Woodrow said the concrete dock measures 49 metres (160 feet) by 37 metres (120 feet).

It was a floating structure kept afloat with 24 individual, air-tight concrete chambers filled with air, Woodrow said.

"They are air-tight and they are water-tight,” said the information officer.

"We inspect those chambers on a regular basis and we have actually inspected every single one of those chambers in the last two years.”

The structure is also inspected routinely by a diver, the last inspection having occurred in 2011, he said.

Woodrow said he didn't have any information regarding what time the dock started to sink, whether it's sitting on the bottom or how deep the bottom is.

The unofficial word out of Skagway, however, indicates a local resident noticed it sinking at around 6 a.m., and it was totally submerged by 7:30 a.m.

The dock was used to load and unload walk-on passengers and passengers travelling with their own vehicles.

Large sections of both the car and pedestrian ramps were also under water this morning.

Woodrow pointed out there were plans to spend an estimated $1.5 million US to refurbish the 30-year structure over the next couple of years.

The Department of Transportation will be exploring a number of variables over the next few days to see how and when ferry service can be restored to Skagway, he said.

He said variables include everything from salvaging the existing dock to bringing in a floating replacement dock, as well as examining the suitability of other port facilities to handle ferry traffic.

Even if other facilities are suitable, there are still the paper work and formal agreements that would have to be worked out first, he said.