A Royal Navy ship is mapping Jersey's seabed to update the charts leading into St Helier's marina.
HMS Gleaner arrived in June and will be here until the middle of September.
The main routes she is surveying are used by the Royal Navy for conducting high speed navigation training.
HMS Gleaner’s work will only cover a small proportion of the entire Jersey territorial sea but that work is being carried out with sophisticated multi-beam equipment and analytical software.
It will be the first time such a thorough and relatively extensive survey has taken place in many years.
The data will lead to updated charts being produced by the UK Hydrographic Office in Taunton, for purchase by the public.
Under the Safety of Life at Sea (SOLAS) Convention, Jersey has a responsibility to arrange for the collection and compilation of hydrographic data and its publication in order to ensure safe navigation. HMS Gleaner’s work is helping to meet that commitment.
In the longer term the work to extend the survey to shallow areas off Les Minquiers, the east coast and elsewhere will be investigated by the Territorial Seas Consultation and Advisory Group (TSCAG) which brings together representatives from the Economic Development, Tourism, Sport and Culture, Environment and External Relations Departments.
Hydrographic surveys were carried out in Jersey waters in the nineteenth century using rather limited lead-line methods and further surveys have taken place at various times in the 1950s through to the 1990s using more modern sonar equipment.