The Coastal Challenge 6-day ultra race (Costa Rica) ends at a beautiful place called Drake Bay in the Corcovado National Park. I really recommend spending a couple of days down there after the race as there are loads of cool things to do!
Look up the Surf and Turf guys down on the beach, we went on a beautifully breezy quad biking tour to the waterfall we ran through on the last day of the race, and we also chartered a fishing boat and fisherman/captain through them, combining catching Jacks and Black Tuna with snorkelling at Cano Island. The colourful fish and coral will keep you enthralled for hours, swimming in bath-water seas. On our return, our guide gutted the fish and took us to the restaurant next door and instructed the chef to cook it just how we liked it, for a hugely reasonable price! It was DELICIOUS. Nothing better than catching your own fish and eating it, yum! (Unless vegetarian or vegan, sorry if you are!)
We also did a nighttime frog and spider tour which was excellent, you can book these from pretty much all the hotels and self catered accommodation in this tiny village. Just take a walk about and choose your tour!
Have fun in Costa Rica!