Divers in Indonesia can observe a greater concentration of different tropical marine species than anywhere else in the world. New species are found regularly.  The reason for such diversity is that the Indonesian archipelago is strategically sited in the exact center of the oceanic area encompassing the Indian and Pacific oceans.  This area (called Indo Pacific) is home to the same species as those found in Hawaii and the Red Sea.  While it would be rare to find species from the Red Sea in Hawaiian waters and vice versa, in Indonesia all types of species are flourishing together.  An excellent reason to come diving here.  

Bali has some impressive dive sites.  With pleasant temperatures of average 27'C year round and good visibility, the best time of year for diving is the dry season from April to October.  The wet season from November to March can be quite torrential.  

A lot of the diving and snorkeling areas are very close to the shore with lots of colorful hard and soft corals and an amazing range of tropical fish.  For the moment the reefs are mostly unspoiled and a wide variety of marine life such as dolphins, rays, turtles, Sperm and Blue whales, sea snakes and moray eels can be found here.  
  
The main diving and snorkeling areas in Bali on the East Coast are at Padang Bai and Candi Dasa and further north at Tulamben and Amed.  Following the coastal road in the north of the island is Lovina.  Slightly further along is Pemuteran and in the western tip of Bali is Labuan Lalang, the kick-off point to Menjangan Island, an uninhabited island with some of the best diving on Bali.  Nearly 7000 hectares of coral reef and coastal waters are protected as part of the Bali Barat National Park including Menjangan Island.  

In southern Bali, there's a reef in Sanur and the island of Nusa Lembongan, Nusa Penida and the Gili islands off Lombok are all popular diving destinations.  Bali has an abundance of dive operators - many based in Southern Bali who will transport you to the main dive areas or you can also stay at most of the locations to save on travelling time.  You can get certification if required.  Certifications available are PADI, SSI, CMAS and the local POSSI certification.  
  
SANUR/NUSA  DUA  
Often used as a location for teaching diving because of it's close proximity to the tourist areas, there are some interesting coral formations, sponges and plentiful colorful fish on the reef at Sanur.  
  
CANDI DASA  
Batu Tiga  (Three rocks) is accessed by boat from Candi Dasa or Padang Bai.  With an average depth of 20m, the site is excellent for diving or snorkeling.  The reef is steep and sloping with many corals.  Some fish seen here include Red Snapper, Clown Triggerfish, and Blue Spotted Stingrays, Trivially, Morays and Whitetip Reef sharks.  

Pulau Tepekong - On the east and north sides of the island this is a wall dive with many caves.  There are large biomes and many fish such as different Triggerfish, Angelfish, Snappers, Butterfly fish, Parrotfish, Moorish Idols and Emperor.  
  
AMED  
Amed has excellent snorkeling just off the black sand beach and further out in the bay there is a coral wall with an abundance of sponges and hard and soft corals. Fish varieties include Black Snapper, Triggerfish, Surgeonfish, Unicornfish, Parrotfish, Damselfish, Cardinalfish, Whitetip Reef Sharks and many larger varieties such as Dogtooth Tuna and Blue Finned Trivially.  
  
TULAMBEN  
One of Bali's most popular diving sites is the wreck of the US Liberty warship.  The Japanese during World War II torpedoed it in the Lombok Strait.  She was beached on Tulamben when rescue attempts failed.  After the eruption of Mt.  Agung in 1963 she broke in half and was left in her present position close to the shore of Tulamben.  The hull is encrusted with coral and the fish have become quite tame because of the large numbers of divers here.  
  
LOVINA  
A popular beach resort area, Lovina refers to a collection of small villages on the coast.  In the past coral in the bay was used to make lime.  Fortunately the coral is now protected and some diving and snorkeling is possible with very clear water.  Lovina also is a good place to stay if you want to go to Menjangan.  

PEMUTERAN  
This area has suffered a bit from dynamite fishing but great efforts have been made to stop further destruction.  There is much coral available such as Elkhorn and Staghorn.  There are many tropical reef fish and a profusion of Moorish Idol.  There is also a turtle sanctuary located at Pemuteran with regular releases of turtles into the sea, which have been bred at the Sanctuary.  There is also good snorkeling available right off the beach.  
  
MENJANGAN ISLAND (DEER ISLAND)  
There are a few dive sites to choose from at Menjangan with good conditions and excellent visibility.  The snorkeling is excellent too.  Menjangan also has a wreck, known as the "Anker" because of it has heavily encrusted anchor at the top of the reef.  Fixed moorings have been built to prevent damage and the island is reached by a 30-minute boat ride from Labuan Lalang.  
  
NUSA PENIDA  
About one and half-hours from Bali by motor boat, Nusa Penida offers some truly spectacular and unspoiled diving and snorkeling.  As there is not much development here, the reefs are pristine.  An abundance of hard and soft corals makes a home for large amounts of tropical fish such as Angelfish and Clownish.  Moray eels live in the crevices and Whitetip Reef Shark’s search for food at night and sleep by day under table corals.  
  
NUSA LEMBONGAN  
The smaller island of Nusa Lembongan is a popular destination for day-trippers.  At the northern end of the island, Mangrove Point, Crystal Bay and the Blue Comer Trip are all good diving sites. Some of the areas are for experienced divers only and look for Manta Point to the east where schools of Mantas come to the cleaning stations and to mate.  
  

Surfing  

While most People believe that Bali's magnificent surf was first discovered by Australian surfers at the end of the 1960s, the truth is that it was Robert Koke, founder Of the Kuta Beach Hotel in the 1930s who was the first man to surf the break.  He had learned to surf in Hawaii and after settling in Bali; he had one of those enormous teak wood boards sent over.  The Balinese thought he was crazy, but as pioneer.  

Bali is surfer’s paradise Not only does it have a wide variety of beaches and breaks to choose from, the surf here is constants Unlike many other places, there is always a decent wave somewhere on the island and often magnificent waves in several places.  
Kuta: By far the most famous surfing beach in Bali.  There are numerous spots along the Kuta Legian strip offering great waves.  Depending on the season, these can be large or small but are usually surfable.  Be careful, as there are some powerful rips around.  Also, remember your surf etiquette.  It can be pretty crowded out there on good days and some people can be quite hot headed about who was first.  There are numerous places to rent boards along the beach.  

Uluwatu: In the shadow of one of Bali's holiest temples perched atop sixty meter limestone cliffs, Uluwatu is not only a magnificent sight but also one of the most challenging surfing beaches in the world.  As a rule, the waves are big and frequently monstrous.  Unfortunately for those with more courage than skill, they break straight onto the reef, meaning that if you are not really a competent surfer, there is a good chance that you will come up looking like a hamburger.  For surfing voyeurs this is the place to go to watch those big tanned bodies put to the test.  
All along the perimeter of the Bukit, southern Bali's highland peninsula, there are a number of great beaches frequented by surfers Formerly very isolated, new projects such  
Pecatu Indah has made beaches like Dreamland and Padang Padang easily accessible.  Like Uluwatu, the waves hare usually break into the reef.  In addition, few have channels meaning that you have to paddle like a maniac to get out there.  

Reef Breaks: There are two outstanding reefs break in Bali, 1 in Kuta and the other in Sanur.  Most hire a boat, usually a local outrigger, for a half-day to carry them out and in with leisure.  Sometimes the boat simply drops you off and will pick you up later.  Sanur reef is a real pleasure as here is a channel that will carry you back out to the surf after you have caught a wave, meaning you won't have to paddle like a madman.  
Besides having great surfing, Bali is also the starting point for expeditions to further and more exotic destinations.  By far the most popular is Grajagan, off the coast of southern Java.  This is where the world championships were held.  The waves here are second to nowhere in the world, including the legendary Pipeline.  The best place to find out about all this is at Tubes, which functions as the local Surfing Central.  Until then just remember Surfer's Up and if you have not surfed in Bali, then you have not surfed at all. 
 

Source : Bali Visitor Guides