A survey to chart the underwater history of Scapa Flow has been launched in Orkney.

Researchers from Heriot-Watt University in Edinburgh are producing three-dimensional images of German ships scuttled off the coast.

The naval wrecks of Scapa Flow form a unique underwater record of British and German maritime history.

The ships of the German high seas fleet were interned and then scuttled in 1919.

Groundbreaking research

Seven of the sunken wrecks remain off the islands and each year more than 2,000 divers flock to explore them.

The researchers from Heriot-Watt are using sonars to produce images of the vessels and the debris around them.

It is being described as a groundbreaking research project to map the area.

Marine scientists hope their work will promote better management of the archaeological heritage of Orkney's submerged past.

The survey should be completed next week and the data will then be used to build up an interactive computer tour around the wrecks.

There is also a plan for an exhibition so that the public will be able to see sights which have until now only been accessible to divers.

Container port

The vessels off the Orkney coast also include the HMS Royal Oak, which was torpedoed by a German U-boat at Scapa Flow on 14 October 1939 with the loss of 833 lives.

In February, a feasibility study commissioned by Highlands and Islands Enterprise said that plans for a container port in Scapa Flow were "commercially attractive and should be taken further forward".

The development, if approved, could cost up to �470m.

Highlands and Islands Enterprise said the container port could be operational by the year 2006 if a funding package is approved.

UK Defence Minister Lewis Moonie has launched a consultation exercise aimed at ensuring the protection of military sea graves.