Middle Arch
Depth is the range from the top of the site to its usual maximum; "recommended cert" is the mainstream-agency level operators usually ask for, not a legal rule. Currents and visibility change daily — treat everything here as planning ranges.
Middle Arch is the mellow sibling of the Knights' famous slots, wide enough to feel like a boulevard and shallow enough for long, gas-friendly dives. Scorpionfish impersonate rocks along the walls, moray eels share crevices with crayfish in a reserve where both grow old, and the kelp fringe swirls with demoiselles and butterfly perch. Nudibranch hunters do some of their best work here, and a small side cave scribbles bonus dark corners onto the map. Guides use it as the all-weather, all-levels anchor of a Knights day, and it never feels like a consolation prize.
The moment you come for: Broad easy archway, crayfish and morays in the cracks, prime nudibranch hunting
Topography: Broad archway with kelp-edged walls, boulder slopes, and sandy patches
Know before you splash
Hazards: Mild surge near the walls in swell; otherwise benign.
Who you'll meet
For photographers
Wide angle: ★★★★☆ · Macro: ★★★★☆ — editors' 1–5 rating of what this site gives each style of shooting