San José, the vibrant capital of Costa Rica, offers a perfect blend of cultural experiences, lively markets, and beautiful nearby nature. It's an excellent starting point for exploring the country's rainforests, volcanoes, and beaches, making it ideal for a mix of adventure and relaxation. The city also boasts museums, theaters, and delicious local cuisine that both you and your daughter will enjoy.

Guanacaste, Costa Rica, is a fantastic destination for an 18-year-old and her mother looking for a mix of adventure and relaxation. Known for its beautiful beaches, vibrant wildlife, and exciting outdoor activities like zip-lining, surfing, and snorkeling, it offers plenty of fun and memorable experiences. The region's warm tropical climate in June makes it perfect for beach days and exploring nature reserves.