La Catedral is a distinctive natural arch located on the north side of the island of Mouro in Santander. The topography features rock formations descending from the dome to the seabed, creating notable backlighting effects. Depths reach up to 15 metres. Access is by boat. Depending on tidal conditions, wave action against the dome can create significant underwater vibrations and acoustic effects. The site supports a variety of temperate marine life typical of the region, including various reef fish and invertebrates. Divers should be aware that conditions vary, and the site is best suited to those comfortable with the dynamic underwater environment created by the arch's structure.

La Corbera is a diverse dive site near Mouro Island, Santander, featuring a complex topography of walls, caves, and pinnacles. The site is characterised by a landscape of gorges and scattered rock blocks. Divers can explore specific features including a cathedral formation and the Cueva Grande. This site is suitable for intermediate divers, with depths ranging from 10 to 18 metres and an average of 15 metres. Access is strictly by boat. Conditions include moderate currents and visibility between 5 and 15 metres. The habitat supports a variety of temperate marine life and invertebrates typical of the Cantabrian region. Dives typically last 50 minutes.

Las Agujas consists of two rock pinnacles located northwest of the island of Mouro. These formations rise from the seabed to within 7 metres of the surface, with the base reaching depths of 18 metres. Divers typically explore the pinnacles in a circular route before heading south towards the island to conclude the dive at La Cala. Access is by boat, which is required for this site. Conditions are variable, and divers should be prepared for strong currents that may require navigation by compass. This site is suited for intermediate divers due to the potential for challenging current conditions.

La Cala is a dive site located near the island of Mouro, which has been a special protection area since 1985. The site features a mix of sandy bottom and rocky areas, providing a habitat for various regional marine life. Dives here are conducted from a boat, with depths ranging from 5 to 10 metres depending on the tide. The site is suitable for beginners, though divers should remain aware of variable currents and boat traffic in the area. Water temperatures fluctuate throughout the year, ranging from 13C in winter to 22C in August.

The Pecio Rio Miera is an English coal freighter wreck resting at depths between 38 and 42 metres, with an average depth of 41 metres. The vessel, which features a stern engine and three masts, sank in 1951 following a collision. This advanced dive requires boat access and is located approximately 6,436 metres from the shore. Divers should be prepared for strong currents and the challenges of an overhead environment. Visibility at the site typically ranges from 15 to 20 metres. The habitat supports various temperate marine life, including reef fish and invertebrates common to the region. Water temperatures fluctuate between 13C and 17C throughout the year.

Pecio Skotland is a wreck dive located 1000 metres offshore from Santander, Spain. The vessel lies at a depth of 42 to 45 metres, with an average depth of 44 metres. Due to the significant depth, this site is strictly for advanced divers and presents hazards including decompression, nitrogen narcosis, and the risks associated with deep diving. Access is exclusively by boat, and the site is subject to moderate currents. Divers should be prepared for water temperatures ranging from 13C to 16C throughout the year. The wreck remains provide a structural environment for exploration, requiring careful planning and appropriate technical training for safe navigation.

Isla de los Conejos in Santander offers a diverse underwater experience combining reef, cave, and drift diving. Located in the Cantabric Sea, the site features depths ranging from 12 to 20 metres with an average of 16 metres. Divers encounter moderate to strong currents, necessitating strict adherence to boat entry and exit procedures. Visibility typically ranges between 5 and 10 metres, requiring divers to focus on the reef and cave structures. The site is suitable for beginners, though the current requires careful attention to timing and positioning. Water temperatures fluctuate between 13C and 21C throughout the year, making appropriate thermal protection essential for all dives.

Punta Ballota is a reef dive located in the Cantabric Sea near Santander, Spain. The site is suitable for beginner divers looking to gain experience in Atlantic coastal conditions. The reef lies at depths between 15 and 18 metres, with an average depth of 17 metres. Divers should expect moderate currents and visibility ranging from 5 to 10 metres. Access to the site is by boat only, and typical dive times are approximately 45 minutes. Guided tours are available, and air fills can be obtained locally. Water temperatures fluctuate significantly throughout the year, ranging from 13C in winter to 21C in August.