La Boquita, naturally protected by the shape of the bay, it is probably the safest place for swimming in Manzanillo, Mexico as there are almost no waves or currents.
Along the beach side there are various ramadas - small thatched restaurants, that offer delicious fresh seafood at very reasonable prices. Here you can pay local musicians to play for you as you enjoy some mariscos (seafood) and a cold beer.
If you are feeling adventurous you can snorkel out to the ship wreck or coral reef, where you will see lots of colourful fish. Over the lagoon side it is generally quieter, you can hire a table, chairs and umbrella for the day and relax or play in the water. Perfect for children as the water is super calm.