Biscoitos Gate is a technical dive site off Terceira, defined by its vertical wall and cave topography. Located at depths between 32 and 36 metres, the site requires expert-level buoyancy and gas management due to the overhead environment. Divers should expect moderate currents and variable visibility, which can fluctuate significantly within the cave sections. Water temperatures range from 16C to 21C, necessitating appropriate thermal protection. Access is exclusively by boat, and divers must confirm descent line availability with their operator. Species recorded around this area include common octopus, Turkish wrasse, various crabs, and bream, alongside other Atlantic deep-reef assemblages.

Abismo Arco is a marine dive site located off the coast of Terceira in the Azores. The site features a combination of reef, wall, and cave topography, offering a varied underwater landscape for intermediate divers. Depths range from 5 to 37 metres, with an average depth of 20 metres. Access to this site is by boat only, as it is situated approximately 9656 metres from the shore. Divers should be prepared for moderate currents, which can occasionally become strong. Visibility at the site typically ranges between 10 and 30 metres, and water temperatures fluctuate between 16C and 21C throughout the year.

Biscoitos Cavern is a shore-entry cave and reef dive on Terceira, featuring depths between 18 and 23 metres. This site presents an overhead environment that requires advanced diving experience and precise buoyancy control. Divers should be prepared for low-light conditions and carry primary and backup torches. While currents are typically mild, surge and swell can move unpredictably within the cavern, necessitating careful monitoring of conditions. Species recorded around this area include various Atlantic reef fish and invertebrates. Divers must be self-sufficient, as facilities are unconfirmed. Always check the sea state before entry, as surface swell can funnel into the cavern and affect conditions at depth.

Cinco Ribeiras is a coastal site on the south-western side of Terceira, defined by lava flows that have created distinct lava arches and tubes. The site is home to a notable underwater cave and the remains of the Union, a vessel that sank in 1911; divers can still observe the ship's boiler. With depths ranging from 1 to 16 metres and an average of 12 metres, the site is suitable for beginners. Entry is via the shore, and conditions feature mild currents with visibility between 10 and 30 metres. Night diving is permitted, and typical dives last 45 minutes. Divers should be aware of the overhead environment hazard.

Arraia Reef is a sheltered shore dive located in the Silveira swimming zone, protected from wind and currents by the Monte Brasil volcano. The topography features a shallow rocky bottom that transitions into a sandy area, deepening as divers move away from the bay. With depths ranging from 5 to 15 metres and an average of 14 metres, this site is suitable for beginners. Visibility typically spans 10 to 30 metres, and the site supports night diving. Facilities at the entry point include showers and changing rooms. Divers should be aware of sharp coral present at the site.

Poente is a reef site located 5000 metres off the coast of Terceira, Azores. Designed for intermediate divers, the site features depths ranging from 18 to 22 metres with an average of 20 metres. Divers experience mild currents and visibility between 10 and 30 metres. Access is exclusively by boat, and divers must deploy an SMB before surfacing due to potential boat traffic. The site is suitable for night diving, which can offer different observations along the rocky substrate. Water temperatures fluctuate seasonally between 16 and 23 degrees Celsius. Divers should be aware of sharp coral and maintain direct boat entry and exit procedures to manage the current.

The Vapor Lidador is a 78.67-metre British steamboat wreck located 50 metres from the shore of Terceira, Azores. Built in 1873, the vessel served the Portugal-Brazil route before sinking in 1878 after striking a shoal near the fortress of Sao Sebastian. Now part of the Archaeological Subaquatic Park of Angra do Heroismo Bay, the wreck lies at depths between 8 and 11 metres, with an average depth of 8 metres. This site is suitable for beginners and accessible by both boat and shore. Divers can expect mild currents and visibility ranging from 15 to 40 metres. The site is also open for night diving.

The Lidador is a deliberately sunk wreck located 50 metres from the shore of Terceira, Azores. Resting at depths between 8 and 11 metres, the site functions as an artificial reef suitable for beginners and those building confidence. Divers and snorkellers can access the wreck from the shore or by boat. While currents are generally mild, the site is subject to surf and potential surges, requiring careful planning for entry and exit. The wreck is accessible year-round and is a popular location for night dives. Always remain aware of local boat traffic when near the surface and check current conditions before entering the water.