I’m not too crazy about Playa del Coco. It’s more of a loud party town if that’s your thing. Its only an hour bus ride away from Liberia.
The beach area is not to bad. Walk for about 10 minutes west on the beach and it gets pretty nice. Watch out for thieves. I would not bring anything to the beach. The locals are even scared to bring anything.
I witnessed a kid snatch a bag on the beach and then on my bus ride to San Jose a guy had his bag stolen with his laptop and passport. It can make a vacation unpleasant.
Diving: Not any reefs around. Mostly rock formations I was told by local dive shop.
Playa del Coco has some nice restaurants and a good cigar/coffee shop. Three internet cafes.