6 - Oceanside Harbor to San Luis Rey. 9 miles (one way), 131 ft el, 15 ft/mi

0.0 The entrance to the bike trail is the sidewalk on the northwest side of Neptune.
8.9 U-turn Santa Fe and Hwy 76
17.8 return to start

This is a great bike path, one of the longest in the county. Scenic and pancake flat.
Be sure to stay on the bike path as it dips under streets to avoid dangerous street crossings.
Watch out for dogs, strollers, children, oncoming bikes, etc. A Saturday morning on this bikepath and you will appreciate how predictable and respectful cars are in comparison.
Be polite - call out "On Your Left!" as you approach pedestrians from behind.