Bali has many great beaches - good for swimming, surfing, or just lounging on the sand. Some hotels and villages provide daily clean up and grooming of beaches. Also, the quality of a beach can change drastically between seasons, depending on the location of the beach and the direction it faces.
Here is the subjective Bali Best Beach list:
1. Nusa Dua from Hyatt to St Regis/Geger Temple.
Known as Mengiat Beach and Geger Beach. The most beautiful blue water, pristine white sand, minimal vendors. You can use this beach anytime (without staying at one of the hotels) at the Yasa Segara village or Geger village beach cafes, which are open to the public. The cafes rent beach chairs for about 20k rupiah per day and food/beverage is available from the cafe. There is also a parking lot. Geger is one of the few beaches at which topless sunbathing is allowed.
2. Jimbaran. Waves and white sand.
Beach is accessible from the Jimbaran barbecue restaurants, but is really best when staying at a beach front resort. Most of the beach is not really suitable for use unless staying in one of the local hotels. At the south end of the beach is the Four Seasons, with a private beach club and restaurant (PJ's - recommended). The beach directly in front of the Four Seasons is rocky and rough, not really suitable for swimming. The beach is more inviting 50 meters away towards the beach cafes.
3. Sanur area.
Favorite of many visitors for its old time flavor and local feeling. There is a 7km paved walkway along the beachfront which is great for early morning walks. Excellent spot to take sunrise photos. Numerous breakwaters with shelters have been placed along the beach to protect the beach from erosion. The area around the Bali Hyatt seems to be the nicest white sand beach. This was the first developed resort area on Bali and is very popular.
4. Kuta/Legian/Seminyak/Kerobokan/Batu Belig.
Nightlife, sunset and beach. Beach is not as clean as Nusa Dua and most areas of Jimbaran and the water is rougher. Lately, clean up crews have been noticed in the morning. Close to great restaurants and night life. Nightly sunset is a plus and many beach front resorts and restaurants have beach side lounges to enjoy this scenery.
5. North Nusa Dua area, from Melia Hotel to Novohotel Tanjung Benoa
6. "Echo Beach" Cangu
Increased in popularity recently due to the vibe from the restaurants built on a cement seawall facing the ocean. Echo beach really isn't suitable as a swimming or relaxation beach, but has a solid reputation as a surf beach. The beach is a bit rocky and the sand is blackish and the seawall on which the restaurants are built is not attractive. The surfing attracts a crowd of surfers and watchers, and it is enjoyable to watch the action from the seawall while enjoying the cuisine from the The Beach House or other warungs. The road to Echo beach has become very pitted and is in need of improvement.