The main beach in Coco is under renovation with a new boardwalk but it is still not the best looking beach. However, it's a great place to rent a boat for an excursion to nearby "Gorilla rock" also known as "monkey's head rock" as well as some mangrove swamps up the coast. A boat can also take you to some very good quality snorkeling just off-shore. If you decide to rent a boat, be sure to negotiate hard. Often times you will be asked to pay twice as much when you first ask for a price.
If you have a rental car, you can drive to either Ocotal or Hermosa beach. Both of these beaches are much cleaner and only 5-10 minutes drive away. If you're looking for a nicer beach and/or a longer trip, you can drive over to the Four Seasons Papagayo, park just outside the front gate, and then walk to the beach in Costa Rica, all beaches are public, so they can't stop you from hanging out on their "private" beach.
A local resident named Dr. Will (http://www.greenmysteryco...) offers an early-morning wildlife tour that will introduce you to Costa Rica wildlife right under your nose. Will is a retired veterinarian who lives in nearby Ocotal and offers individual tours for $30-40 per person, depending on the group size.
Deep sea fishing excursions are definitely available as well - be sure to ask around on the beach in the late afternoon to find the best deal for the following day. You can also hire a boat to take you surfing off-shore near world famous Witch's Rock just up the coast from Coco. However, if you're new to surfing or not willing to invest in an all-day boat tour, you might consider driving about an hour to nearby Tamarindo. The surfing there is very good for beginners and kids.
There are many reputable dive companies in town including Summer-Salt (http://www.summer-salt.com), and Deep Blue Diving (http://www.deepblue-divin...). Both employ people who have great depth of knowledge of not only what is in the ocean but what you can find on land. If you want to go sailing the Kuna Vela (http://www.kunavela.com)
Finally, much like any tourist-oriented community in Costa Rica, you will find organized jungle tours that include zip-line rides. While there are half-a-dozen local tour operators and zip-line operations, you might consider visiting the Hacidenda Gauchipelin (http://www.guachipelin.com) for an all day package that includes a good quality zip line tour, and then your choice of a waterfall visit, a horseback ride, a soak in a mud bath, etc. Hacienda Guachipelin is about an hour away from Coco, but it's reasonable value and offers nice views of the dormant volcano Rincon de la Vieja.
El Viejo Wetlands - Palo Verde Tour
Activity Choices · Palo Verde by Boat · Eco Ride / Electric Shuttle · Canopy Tour · Sugar Mill Trapiche