Los Arcos, Puerto Vallarta: Arches, Walls, and Reefs

Los Arcos itself is a series of granite islands, just south of Puerto Vallarta, whose submerged bases create a complex reef system. The site offers a range of underwater landscapes, from sheltered shallows that are ideal for divers gaining confidence to deep walls that challenge experienced divers. Beneath the surface, these formations transition into a series of arches, tunnels, and dramatic drop-offs that define the unique profile of the area.

One distinct zone, known as El Acuario, presents a shallower profile, typically between 9 and 12 metres. Here, you’ll find yourself navigating among schools of angelfish, pufferfish, and butterflyfish that glide across the reef. Trumpetfish often hover vertically, blending into the rock work, while parrotfish graze on the corals. Keep an eye out for seahorses (Hippocampus) tucked away in the calmer sections, alongside green sea turtles (Chelonia mydas) moving deliberately through the water.

Venturing to the western side of Los Arcos reveals a more dramatic topography: a vertical wall, extending beyond 40 metres. This area, particularly the section known as El Cañón del Diablo, starts its descent around 18 metres but the main dive often takes place between 24 and 36 metres. Here, the structure allows for encounters with bright schools of reef fish, while moray eels (Muraenidae) are frequently seen in crevices. Oceanic manta rays (Manta birostris) and green sea turtles (Chelonia mydas) are also occasional visitors to these deeper sections.

Beyond the main wall, El Bajo del Cristo offers a dive around a submerged pinnacle and volcanic rock formations, with depths from 9 to 24 metres. This area is teeming with life, from parrotfish and snapper (Lutjanidae) to various species of moray eels (Muraenidae). Nudibranchs (Nudibranchia) are common on the rocky surfaces, showcasing their vibrant colours. This varied structure creates numerous hiding spots and foraging grounds, supporting diverse species you might not encounter in the more open sections of the site.

The geological makeup of Los Arcos, featuring these significant volcanic formations and canyons, distinguishes it from many other reef dives in the region. The interplay of light and shadow through the archways and into the deeper canyons creates a distinct atmosphere, a sense of exploration unique to this site. It's this combination of accessible shallow reefs and challenging deeper structures that defines the experience, catering to a range of diving preferences.

For divers seeking a deeper experience, some parts of Los Arcos feature extensive coral gardens and large black coral colonies, particularly noticeable beyond 25 metres. These deeper zones involve navigating through substantial canyons, where you might find spiny lobsters (Palinuridae) and more moray eels (Muraenidae) in the protected alcoves. Angelfish (Pomacanthidae) and boxfish (Ostraciidae) are common sights, alongside smaller creatures like shrimps (Caridea), crabs (Brachyura), and pipefish (Syngnathinae) that blend into the reef structure.

The prevailing conditions at Los Arcos typically involve a mild current across most of the site, making it suitable for drift diving and detailed exploration without fighting against strong forces. Visibility generally ranges from 6 to 15 metres, providing clear views of the diverse marine life and complex rock formations. The water temperature, consistent with the region, ranges from 17°C to 30°C depending on the season, making a 3mm or 5mm wetsuit a comfortable choice.