From the South or North of the UK most people will drive to Mersea Island.
Head to the A12 from the north, south, east or west of England and then drive towards Colchester - there are signs to Mersea off the A12.
The nearest main town is Colchester followed by Ipswich.
By train you can travel to Colchester and then get a taxi to Mersea Island (about 25 minutes drive)
If flying Stansted Airport, Essex is your nearest airport - about one hour away by car.