The Cathedral Cave, on 'Eua Island's northern tip, has long been regarded as one of the best dive sites in Tonga as well as in the South Pacific. It is a popular scuba diving spot that was discovered in 2001. It has a large cathedral and a 100-meter-long, 50-meter-wide, and 30-meter-deep underwater cave system. The cave has two entrances, one on the ocean side and the other on the land side, which are typically used by divers. The entrance is at 28 meters and is in a "current prone" area, so free diving is possible.

The Cathedral Cave has a large network of caves that experienced free divers can explore. With natural light filtering down to a sandy bottom 25-30 meters below, this amazing site is an underwater photographer's dream. The cave has a variety of entrances and provide a spectacular break from spearfishing or whale swimming. The cave system is home to crayfish.

• Max Depth: 30m
• Location: 'Eua, Tonga

Many of Vava'u's incredible natural wonders are actually beneath the sea's surface. Scuba dive at some of the group's incredible and colorful dive sites, such as China Town on Tu'ungasika Island, to see a different side of Vava'u. The name of this dive site comes from the pagoda-like coral formations that can be found there. You will find beautiful fields of red anemone and its resident clown-fish.

Here, you'll find some unusual coral formations that resemble Chinese architecture, as well as a variety of fascinating tropical marine life. At this nearby dive site, coral has been inspired by Chinese architecture. From multi-colored tubeworms to bright red anemones, this fascinating dive site is home to a plethora of colorful creatures. Clownfish, sleeping sharks, emperor angelfish, triggerfish, and lionfish are among the many species that can be found in the tunnels and crevices.

• Max Depth: 27m
• Location: Tu'ungasika Island, Vava’u, Tonga

The Clan MacWilliam was a 140-meter-long steam-powered cargo ship that sank on the 25th of December 1927 in the Port of Refuge Harbour after a fire in its cargo hold. The wreck is only 30 meters deep in Vava'u's Neiafu Harbour, making it accessible to certified divers of all levels. Soft and hard coral cover the wreck, attracting a variety of colorful reef fish.

Larger schooling fish buzz past the upper deck, handrails, and superstructure, which are covered in a variety of hard and soft corals. It's worth bringing a torch to see into some of the larger compartments because there's a lot of macro life on the wreck. The Clan MacWilliam wreck is a great night dive and a great training ground for those looking to improve their diving skills. The wreck's middle section and superstructure have now collapsed inwards. You should avoid penetration diving because the ship is becoming unstable.

• Max Depth: 40m
• Location: Vava'u, Tonga

The Ha'apai island group also has a number of fantastic dive sites, starting with Hot Spring Cavern. The Cave is not only one of most beautiful dive sites in Tonga, but also one of the most wonderful diving sites in the Pacific. This is a dive you won't soon forget, with an underwater hydrothermal vent gushing into the cooler cavern waters! Apart from temperature changes, the dive site also has sponges and corals just before diving into the 22-meter cave entrance, which has a depth of 15-30 meters.

The Hot Spring Cavern system itself was formed by hot thermal springs forging a cave system through the rock. Thermal vents churn out warm water into this cave system, so you'll feel the occasional surge of hot water as you dive. In the center of the hot springs is a large crater that emits large quantities of warm water and gases. The pressure from the air bubbles pushing through the crater on the lake floor causes the surrounding rocks to vibrate slightly. Divers can usually feel these vibrations themselves, which is a unique experience!

• Max Depth: 30m
• Location: Ha'apai, Tonga

The Arch of Ofalanga, a 20m wide and 15m tall arch that is incredible to explore, is another adventure in Ha'apai. The Arch of Ofalanga is a magnificent coral arch formation that formed during the last ice age and is the most popular dive site in Ha'apai. The arch stretches 30 meters beneath the surface, frosted with the craggy life of hard corals, while the soft coral's pink, yellow, and purple hues provide incredible textural variety, leading you along a coral arch formed during the last ice age.

When looking at the arch, you'll notice a lot of crustaceans on the underside, as well as the arch's and surrounding reef's shadows. If you're an avid underwater photographer, this location couldn't be more ideal for creating truly stunning underwater images. Keep an eye out for massive crayfish clinging to the roof and sides. This is a dive that only experienced divers should attempt.

• Max Depth: 28m
• Location: Ha'apai, Tonga

With massive coral bommies outside, and astonishing swim throughs, tunnels, and overhangs inside, J-Caves is one of the most beautiful dive sites in Tonga you can experience. This dive site is as diverse as its marine life; along the way, you can see eagle rays, whitetip reef sharks, and critters like whip coral shrimps and bubble coral orangutans, as well as an array of coral. On your way back up to the surface from maximum depth at 28 meters, you’ll see some amazing macro life if you look carefully. Most certified divers can dive to a depth of 28 meters in J-Caves.

The stunning caves and tunnels lead to a hotspot of thick hard and soft corals, as well as macro life and reef fish. A colourful metropolis of fish life, you will no doubt be eyed by the schools of fish standing close to the pastel colours which they call home. The J-caves are home to reef sharks, manta rays, and eagle rays.

• Max Depth: 28m
• Location: Ha’apai, Tonga

One of those rare and truly amazing experiences that happen once in a life time, the Hunga Magic trip involves a short journey to the calving grounds of the Humpback Whales. It is a stratovolcano, a cone-shaped type of volcano that usually produces only minor volcanic activity. Eagle rays and white tips can sometimes be seen but keep an eye out for the critters on this one.

Hunga Magic is one of the best places to see humpback whales for divers. Between the middle of July and the end of October, humpback whales come to Tonga to mate and calve, and quite often, one can snorkel or dive with them. Divers, on the other hand, will need to make arrangements through a licensed tour operator. Any planned encounters with whales are limited to snorkeling only. Otherwise, Vava'u's Hunga Magic offers a beautiful reef dive site with a variety of coral, including leather coral, carnation corals, stone corals, and more.

• Max Depth: 16m
• Location: Vava'u, Tonga

Tongatapu's dive sites are limited in comparison to Tonga's other island groups. If you want to get away from the hustle and bustle of Nuku'alofa, take a dive boat to the Outer Reef. It is one of the most beautiful dive sites in Tonga, where you'll be able to see some amazing things. This dive takes you out of town and allows you to see the beautiful canyons, caves, and drop-offs that are not protected by the reef.

Larger pelagics such as reef sharks, rays, turtles, and crustaceans can be found in the shadowed turrets and overhangs of the corals on each dive. Unafraid trevallies, cautious barracuda, defiant napoleons, and vibrant schools of parrot, damsel, and butterfly fish will all add color to your dive. On the whip coral, tiny whip coral shrimp make their homes, and nudibranchs and crustaceans can be found as well. Be sure to look for Orangutan crabs among the bubble coral!

• Max Depth: 35m
• Location: Tongatapu, Tonga

Swallows Cave is located at the northwest tip of Kapa Island in Vava'u, in The Kingdom of Tonga. Swallows Cave, one of the best diving sites in Tonga, is also a great place to go scuba diving and a cool dive site in Vava'u. With its beams of light shining through the entrance and a depth of only 18 meters, Swallows Cave makes for some spectacular dive photography. Thousands of small fish, as well as a few larger fish, will create amazing patterns in the cave.

Swimming near them, murmurations of the swirling groups of the little fish act as one in soft twists and turns producing synchronized entrancing patterns moving in the water around you. Divers and snorkelers alike will be glued to the patterns until they are able to explore the cave walls' deeper depths with colorful nudes and swaying gorgonian fans. It is a popular cave to explore, and because it has a visibility of 40 meters, it is ideal for beginners.

• Max Depth: 18m
• Location: Vava'u, Tonga