Monterey

Monterey sits on the central California coast within Monterey Bay National Marine Sanctuary, designated in 1992 and covering 6,094 square miles of ocean along 276 miles of shoreline, with one of North America's largest submarine canyons reaching depths over 12,700 feet. Diving here is cold-water temperate-reef diving: water runs roughly 8–14°C year-round, so a 7 mm semi-dry or a drysuit with hood and thick gloves is standard, and the signature habitat is the giant-kelp (Macrocystis pyrifera) forest that shelters sea otters, harbor seals, California sea lions, lingcod, cabezon, rockfish, wolf eels, and giant Pacific octopus. The bulk of recreational diving is shore-based and beginner-friendly — Breakwater Cove at San Carlos Beach is the busiest training site on the West Coast — while reservation-only Point Lobos and the steep, canyon-edged Monastery Beach reward more experienced divers. Visibility is variable (typically 3–10 m, occasionally much clearer) and best in autumn and calmer winter windows when plankton subsides; spring and summer upwelling fuels productivity but greens the water. Honest caveats: large stretches of central-California kelp have been lost since the 2013 sea-star wasting epidemic and the subsequent purple-urchin boom, leaving urchin barrens at sites such as Lovers Point, Coral Street, and parts of Point Lobos, though active sunflower-sea-star and urchin-removal restoration is underway; and juvenile great white sharks have aggregated seasonally in southern Monterey Bay since about 2014 — they are a wildlife footnote, not a dive attraction.

• Monterey diving sits inside Monterey Bay National Marine Sanctuary, designated 18 September 1992, which protects 6,094 square miles of ocean along 276 miles of shoreline and is home to 36 marine-mammal species, 525 fish species, and extensive giant-kelp forests over one of North America's largest submarine canyons.
• Diving at Point Lobos State Natural Reserve is strictly capped: only ten teams of two divers (20 divers) are permitted per day, diving is limited to Whalers and Bluefish Coves with entry only at the Whalers Cove ramp, and permits are reserved online up to roughly the current month plus one — weekday $20 / weekend $30 per team plus $10 parking.
• Water temperature stays cold all year — about 8–11°C (47–52°F) in winter and 11–17°C (52–63°F) in autumn — so a 7 mm semi-dry or a drysuit with hood and thick gloves is standard; visibility is typically 3–10 m and best from September through November and on calm winter days when plankton subsides.