A genuinely easy family base by Costa Rican standards — flat, walkable, everything close — with two caveats: the surf here has rip currents, and the town is loud at night.
Playa Jacó itself
A long dark-sand beach right at the end of the street, with shade, food and toilets on the town side. It is a surf beach with rip currents, so keep small children in the shallows and swim near other people rather than on an empty stretch.
Carara's universally accessible trail
A level 1.2 km loop with nine resting bays, built for wheelchairs and therefore ideal for a pushchair or short legs. Non-resident adults USD 10 plus tax, children 2–12 USD 5 plus tax; 8:00–16:00 May to November, 7:00–16:00 December to April, entrance two kilometres south of the Tárcoles bridge.
Rainforest Adventures Costa Rica Pacific
An 18-gondola aerial tram through the forest canopy near Jacó, plus zip lines, a waterfall climb and a serpentarium. The tram is the part small children can do and starts from USD 67.50; the zip lines and waterfall climb have age and size limits, so check before you buy a family combination ticket.
Playa Herradura and the marina
The sheltered bay north of town is flatter water than Jacó's shore break, which matters a lot with under-tens. The Los Sueños marina next to it is a free half-hour of looking at boats, and busiest during the billfish tournaments in January, February and March.
Jacó Walk's creekside trail
A walking trail with native trees, green space and a bike lane running through an open-air centre of shops and restaurants, most open 8:00–21:00. Traffic-free, shaded and on Pastor Díaz, so it works as the release valve on a hot afternoon.