4 mile reef
Why dive here
With 72+ marine species recorded in the area - including blue sharks, dolphins, hammerhead sharks, humpback whales and seahorses - 4 mile reef offers some of Goat Island & Hauraki Gulf's richest reef diving. Water ranges 14-22°C, warmest January, February, March.
Forget the wrecks for a minute. Castaway Island’s house reef, just a two-minute boat ride from the shop, is where we head when we need a reset. It’s a gentle, sandy slope, peaking at 5m, scattered with small coral heads. If you slow down, properly slow down, this place comes alive. We’re talking pipefish: bluestripes, messmates, all tucked into the sand. You’ll spot flounder eyes peeking out, and we’ve found some truly tiny nudibranchs here, often less than a centimetre. It’s a macro heaven, perfect for photographers who like to get low and close. We’ve even seen banded sea kraits hunting through the coral, a sleek ribbon of black and white against the sandy bottom. Visibility averages 13m, which is plenty for this kind of close-up work. It’s our pick for a chill afternoon, a great way to ease back into diving, or just to spend an hour focusing on the small wonders.
Typical 4 mile reef Dive Profile
Illustrative profile based on site depth and type. Actual dive profiles vary - always follow your dive computer and training.
Safety Notes
Cold water this month (avg 14°C). Drysuit or thick wetsuit (7mm+) recommended.
Reviews for 4 mile reef
Conditions
Ocean conditions, forecast and tides for 4 mile reef
4 mile reef Ocean Conditions
Monthly averages for 4 mile reef, sourced from Copernicus Marine satellite data
August Averages
Sea Temperature
14.05°C
57°F
Current Speed
4.24 cm/s
Direction: SE (135°)
Chlorophyll-a
0.301 mg/m³
Moderate productivity
Salinity
35.01 PSU
Data sources: Copernicus Marine Service (EU)
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