Day trip (<1 hour drive from the city) Mount Batur — Hikers will enjoy climbing this volcano, and there are regular sunrise trekking tours organized.
Bali Pulina Coffee Plantation — You'll see the entire process of growing and roasting coffee, with a tasting area overlooking the rice fields (entry fee is 100,000 IDR.)
Weekend trip (>1 hour drive from the city)
West Bali National park — This is a densely forested area you can visit or join a tour, while staying in one of the nearby hotels for the weekend. It's near the Menjangan Island which is one of Bali’s best snorkeling spots.
Gili Islands — Made up of 3 islands: Gili Trawangan, Gili Meno, and Gili Air. You can easily take a ferry from Bali and enjoy the beaches, clear turquoise waters, and spectacular sunsets for the weekend. If you're island hopping, don't miss out on Lombok (a less touristy option) & Nusa Islands!
Bali is a global destination for surfing, you'll find a big surfing community on the island. Join the Bali Surfing Facebook group to get the best advice on renting surfboards and meet fellow surfers. If you're staying longer, join this group where you can buy a surfboard from other travelers, and sell them once you're leaving the island.
Safety Warning: There has been a significant increase in bacterial infections and travelers getting typhoid after swimming or surfing in polluted water. Be careful where you surf - the area around Uluwatu is cleaner than Canggu. Don't go surfing or swimming right after the rain.
Yoga enthusiasts will have a lot of opportunities to deepen their practice on the island. It also has yoga studios with some of the best views of beaches, rice paddies and the diverse nature of Bali.