Running around Attersee, near Salzburg, is just about 50km on roads.

St John is a small island in the U.S. Virgin Islands.  Virgin Islands National Park covers most of the island.  Andy Riddle submitting this route that crosses the center of the island on trails:

A point to point, 83km trail located near Morgan, Gran Canaria and heads north through the island, stopping in Galdar.

The Solent Way is a 60 mile footpath linking Milford on Sea with Emsworth Harbour, much of the path following the Hampshire coast line and passing through the New Forest. Through most of it's length you'll also enjoy views of the beautiful Isle of Wight, just a few miles off the Hampshire Coast. The path is generally way marked with a picture of a sea bird on a green background although the path also forms part of the European Coastal Path (E9) and some signs show this path too, or the name Solent Coast Path.