Public consultation has started on plans to designate an area of seabed off East Mingulay, in the Western Isles, a Special Area of Conservation.
The proposal to give the area such protection was approved by the Scottish government last month.
Ministers said the move would help protect a rare coral reef about eight miles (13km) out to sea.
Scottish Natural Heritage (SNH) said the consultation exercise was expected to run for the next 14 weeks.
People are being asked to comment on the scientific justification for the designation.
SNH will also gather comments on the social and economic affects of protecting the area.
Details of the proposed conservation area are available on SNH's website and in paper form from its office in Stilligarry, South Uist.