Great Barrier Reef, Australia

    Castle

    Best months: Feb–Mar

    Why dive here

    With 154+ marine species recorded in the area - including hammerhead sharks, sea turtles, tiger sharks and napoleon wrasse - Castle offers some of Great Barrier Reef's richest reef diving. Water ranges 24-30°C, warmest January, February, March.

    Best timeFeb–Mar
    WetsuitNo wetsuit needed, or a rash guard
    Marine lifeHammerhead Sharks, Sea Turtles, Tiger Sharks and Napoleon Wrasse · 154+ species recorded
    Water24-30°C · warmest January, February, March
    CharacterReef dive
    StandoutExceptional marine biodiversity

    The Castle, on the Great Barrier Reef, feels less like a dive site and more like a secret passage. We love it for the sheer density of staghorn coral, a real maze that twists and turns. You’ll find yourself finning through narrow canyons, the sunlight dappling through the coral, illuminating schools of Ambon pullers. Keep an eye out for the smaller stuff here; the crevices are packed with Zigzag pygmygobies and Helen’s triplefins. We'd suggest going slow, really taking your time to peer into every nook. The trick here is the late afternoon, just as the sun begins to dip. That’s when the reef comes alive with hunting leopard hinds and the occasional Ringtail Maori wrasse cruising past. It’s not about grand pelagics, it’s about the intricate beauty of a healthy, bustling reef. Perfect for those who appreciate the details and aren't afraid to get up close and personal with the coral.

    Safety Notes

    Strong currents typical this month (avg 30 cm/s). Good buoyancy control essential.

    Today05:5118:1212h 20m daylightGolden hour 17:43

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    Conditions

    Ocean conditions, forecast and tides for Castle

    Castle Ocean Conditions

    Monthly averages for Castle, sourced from Open-Meteo marine data + Copernicus Marine (EU) - nearest station: Open-Meteo marine grid (-15.65, 145.72) (5km away)

    ExcellentGreatGoodFairPoor★Best monthsThis month

    October Averages

    Sea Temperature

    26°C

    80°F · Range: 24.5–29°C

    Current Speed

    30.07 cm/s

    Direction: S (183.8°)

    Chlorophyll-a

    0.057 mg/m³

    Very clear (oligotrophic)

    Salinity

    35.08 PSU

    Based on 4 years of monitoring data · Data sources: Open-Meteo marine data + Copernicus Marine (EU)

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