Isla Seca (or dry island in English) is like a little peninsula that juts out at the end of the beach inlet at Zapallar. It looks like an island from afar because of the rocks on it that elevate the area that sits out in the ocean however it is connected to the mainland and easy to access. We walked around to here from the far side of the beach and climbed part way up - a popular activity with the children in the area. The ocean is quite rugged around this area so it is advisable to save your swimming to the main beach.
The "caleta" or fisherman's wharf is THE place in Zapallar to buy fresh seafood if you want to cook it yourself. Fisherman go out each day and then sell their catch next to the Chiringuito restaurant close to the beach. Many of the people who stay in Zapallar have their maid call the dock early in the morning to reserve such delicacies as "locos" (abalone).
Zapallar is a great place to wander around. Granted, in summer it does get hot, but I think it is a good way to explore the place. Mary, Wini and I wandered around the rocks, along the beach, over to Isla Seca and then up through the town and these pics are of some of the things I saw along the way.
Well, the most obvious reason to go to Zapallar is to go to the beach... and a very nice beach at that!
Be warned though... as with most beaches in Chile the water is very cold due to the Humbolt current. I went in the water in December and came right out again!