A surf shop and school in the middle of El Tunco, renting boards by the hour or the day and teaching beginners on the sand-bottomed end of the beach. Lessons are cheap by any standard and the instructors are local; the shop also sells wax, leashes and the reef booties worth having on a rock-bottom point.
They publish a phone number and an email address, and no street number — El Tunco is two streets, so "next to Ocean Side" is a real address there.