Runners line up at Alnwick Castle to take part in Coquet Yacht Club's Castles and Islands Challenge

Competitors in the Castles and Islands Challenge will set off from the castle at 6pm on Friday (June 23) and will attempt to reach four other castles – Warkworth, Dunstanburgh, Bamburgh, and Lindisfarne by foot – and the islands of North Northumberland – Coquet, The Farnes and Holy Island under sail, all within 24 hours.

The event has been organised by Coquet Yacht Club in Amble, with sponsorship from Alnwick Brewery and tap room, and Standard Security Ltd.

Starting from Alnwick Castle, runners take a 10-mile route to Amble, visiting Warkworth Castle on the way, before continuing to Amble harbour.

There they join their boats, which must circumnavigate Coquet Island in a clockwise direction before visiting Newton Haven, Seahouses Harbour, Holy Island and passing through both Inner Sound and Staple Sound.

This journey can be done in any direction but must be done under sail, and teams must have at least two runners and two sailors, with a maximum of six people per team.

At Newton Haven, Seahouses Harbour and Holy Island Harbour the runners will complete set runs of 4.5 miles, 6.5 miles, and nine miles, to give a combined total of 30 miles of running and roughly 55 miles of sailing.

The challenge has two classes, monohulls and multihulls, and there are various prizes up for grabs.

Challenge Cups are presented to the fastest team in each class that completes the challenge in 24 hours and has the shortest combined running and sailing times.

The All Rounders Challenge is the same but each team member has to complete at least one of the running legs.

There are also prizes for the fastest sailing time; fastest running team that has completed all four runs and the fastest female runner who has completed all four runs.

The Coquet Yacht Clubhouse will be open on Saturday for non-competitors to go along and cheer the competitors on, with a bar from 3.30pm, bouncy castle from 4pm, a food van from 5pm-8pm, and music from 8pm.

Further information about the event can be found at www.castlesandislands.co.uk or on Facebook under Castles & Islands Challenge.