Phu Quoc
Phu Quoc is close to the border with Cambodia and has many great diving spots. It’s great for beginners and an alternative to Nha Trang if you’re looking to certify.
Highlights include Hon Ko or Dry Island where you can see miter shells, bamboo sharks, and catfish. Nudibranch Gardens is exactly what you might suppose. It’s shallow and, apart from nudibranch, you might also see bamboo sharks.
The visibility in this area can suffer due to runoff from the Mekong.
Nha Trang
Nha Trang is a 1-hour flight from Ho Chi Minh and popular with those looking to certify. The twenty-plus dive schools mean that competition is fierce, and that drives the price down.
Notable sites include Madonna Rock, Moray Beach and Electric Nose. Madonna Rock is known for its glass-fish-filled caverns and swim-throughs. The site is made up of pinnacles and home to moray eels, unicornfish, surgeonfish, and lionfish. Keep your eyes sharp, and you might spot octopus, pipefish, and flatworms.
Moray Beach is a popular training site, it can get busy, but it's shallow, with good visibility and a lot to see. Expect clownfish, pipefish, nudibranch, moray eels, lionfish, flying gurnard, sea horses, and razorfish.
Electric Nose is a deep pinnacle which bottoms out at 50m. It’s cloaked in soft coral which hides a variety of macro life waiting to be discovered. The site boasts some 50 or more species of nudibranch as well as shrimps, crabs, flatworms and mantis shrimps.
Whale Island
Whale Island is located 80km (50 miles) north of Nha Trang in Van Phong Bay and is where Jacques Cousteau romanced the ocean. Three Kings is a site comprising of three pinnacles around which it’s possible to see mantas and eagle rays. Whale sharks visit between April and July. The base of the pinnacles is around 30m, and it’s here you find great macro and soft corals.
Cham Island
Accessed from Hoi An, the Cham Islands are a 40-minute boat ride away. Popular sites are Hon Nhan and Hon Mo. The sites are pinnacles and known for pipefish, seahorses, and nudibranch as well as swirling tropical life and colorful corals. Expect hard and soft corals and enjoy trumpet fish and ribbon eels too.
Con Dao
Further south the islands of Con Dao are an archipelago of 16 islands. There’s a wreck here too. It’s here you’re more likely to see pelagic action like turtles, sharks, and rays.
Fish Highway is a site with an optimistic name and a wreck to explore. The 60m long wreck likes at 30m and is encrusted with corals. Expect the usual wreck suspects; grouper, barracuda, moray eels and a handful of camouflage critters too.
The sites in this region are lovely to explore, it’s hard to pick favorites, but Bay Canh, Con Son Bay, Tai Island, and Cau Island will not disappoint.