Lanzarote's northeastern coast became a designated marine reserve in 1995, protecting 70 square kilometres of volcanic seabed and establishing Costa Teguise as one of the Canary Islands' most controlled diving environments. Playa del Jablillo and Playa Chica, separated by 800 metres of rocky shoreline, anchor the town's underwater activity. Both beaches offer sandy entries, depth gradients from three to twelve metres, and year-round water temperatures between 18 and 24 degrees Celsius. The reserve's boundaries extend three nautical miles offshore, encompassing lava tubes, boulder fields, and submerged craters formed during the island's last major eruption cycle in the 18th century. The volcanic substrate creates microhabitats that support angel sharks, cuttlefish, and moray eels alongside temperate Atlantic species rarely seen in warmer Mediterranean sites. Visibility averages 15 to 20 metres in summer and autumn, declining slightly during winter swells when particulate matter rises from the seabed. Costa Teguise diving operations have concentrated here since the early 1990s, drawn by the combination of sheltered bays, short boat-transit times, and predictable currents. The town's location on the island's leeward side shields it from prevailing northeasterly winds, creating surface conditions calm enough for shore-based instruction even when exposed western beaches remain closed. Most diving activity today splits between beginner shore programmes at Playa del Jablillo and multi-dive boat trips departing from the adjacent marina. Shore dives typically follow the bay's eastern wall, descending over terraced lava ledges where barred hogfish and painted combers shelter in crevices. Boat routes reach deeper formations including the Bajón del Río ridge, a 400-metre basalt spine that rises to within eight metres of the surface and attracts schooling barracuda and occasional manta rays during plankton blooms. The reserve's protection status prohibits spearfishing and limits anchoring, preserving coral encrustations and sponge colonies that regenerate slowly in the nutrient-poor Atlantic water. Certified instruction dominates the local industry. Operators offer PADI and SSI beginner courses alongside single-dive introductions that require no prior certification. The emphasis on first-time divers reflects both the calm conditions and the town's position as a family-oriented resort, distinct from the party-focused southern coast. Equipment is uniformly modern, with 12-litre aluminum tanks, balanced regulators, and 5mm wetsuits supplied as standard. The presence of multiple hyperbaric facilities on the island and a coastguard coordination centre in Arrecife provide medical infrastructure that supports higher dive volumes during the peak autumn season.