Sainte-Marguerite is the larger of the two Lérins islands, a kilometre off Cannes and a short ferry from the old port. Three kilometres long, under one wide, no cars and barely any residents. This is a full lap of it, walked anticlockwise: 10.2 km, two hours on the move and half an hour of standing about.
What the camera missed
The video covers the first two thirds and then stops. Filmed: from 0.3 km to 6.45 km, which is the south shore, the eastern point, the north side, the climb and the top of the fort. Not filmed: the descent from the fort, the whole western end with the lagoon, and the return leg — 6.45 to 7.43 km and everything after 8 km.
The map does not stop, though. Drag the dot into those stretches and the readings carry on; the player steps aside and tells you the camera was off.
About the numbers
Distance, height and heart rate come off the watch untouched. The 138 m of ascent is smoothed before it is summed — a barometer left raw counts its own noise as climbing. Average speed is over moving time only. Nearly a quarter of the route sits above twenty metres, and that quarter carries essentially all of the climbing.