Three miles—roughly the distance a person can walk in an hour.
As the sea-shanty Spanish Ladies tells it:
We’ll rant and we’ll roar, like true British sailors
We’ll rant and we’ll roar across the salt seas
Until we reach soundings in the Channel of Old England
From Ushant to Scilly ’tis thirty-five leagues.
The islands of Ushant & Scilly mark either side of the English Channel if you enter it from the Atlantic Ocean. Ushant is near France, Scilly near Great Britain.
Remember—September 19th is Talk Like A Pirate Day!