Recommendation: Bring extra sunscreen & sun shirts
The sun is no joke in Costa Rica. On the first day I got terribly sunburnt, so it was sun shirts for the rest of the trip for me. Because the sun is so hot, it means the ocean is extremely warm!
I stayed in Uvita which is a great town to visit if you like small town vibes, chill beaches, and minimal tourists. Some things to do in Uvita:
Whale Tale Beach
Surfing at Playa Hermosa
Nauyaca Waterfall
Indomitos (great vegetarian restaurant)
The Bakery for coffee & treats
Sunset Body Works for massages
Not in Uvita, but worth the drive: Manuel Antonio National Park (I preferred going without a guide. Quepos is a cute fishing port to stop at on your way)