Mackerel Island

High risk: Ocean Swell & Surge

Swell and surge can wrap around the point, creating strong unpredictable currents and turbulent conditions.

High risk: Deep Water & Boat Access Only

Prime snorkeling/diving sites require boat access; depths range to 40m+ with limited shore exit options.

Moderate risk: Strong ocean currents

The exposed offshore position of The Canyon can experience strong tidal and ocean currents that may sweep snorkelers away from the site.

Moderate risk: Swell and surge

Large Southern Ocean swells can create powerful surge conditions around the walls and swim-throughs, especially in winter months (May–September).

Moderate risk: Strong Tidal Currents

Tidal flows around the island can be strong and unpredictable, especially between the island and the mainland coast.

Moderate risk: Remote Location

The island is uninhabited with no facilities or emergency services nearby; boat access only and limited mobile reception.

Moderate risk: Strong Ocean Swell

The exposed eastern Tasmanian coast receives significant Southern Ocean swell, creating challenging conditions for snorkelers.

Moderate risk: Exposed Open Ocean Swells

Black Jack Reef sits in Storm Bay, exposed to southerly and easterly ocean swells that can create dangerous surge and breaking waves over the reef.

Moderate risk: Strong Wind & Weather Shifts

The Betsey Island Group catches strong winds from the Roaring Forties, which can change rapidly and make conditions unsafe for snorkelers.

Moderate risk: Isolated Location

The reef is offshore near Betsey Island with no immediate emergency services; self-rescue or support boat required.

Moderate risk: Exposed Coastal Conditions

Exposed headland with no shore protection; strong offshore winds can arise quickly, making exit hazardous.

Moderate risk: Strong Ocean Swells & Surge

Exposed to the 'roaring forties' westerly winds, large swells and powerful surge can develop rapidly, especially in winter.

Moderate risk: Unpredictable Currents

Strong, hard-to-predict currents run through the bight, particularly at depth and around the wreck.

Low risk: Cold water temperatures

Tasmanian waters range from 11–18°C year-round, requiring a thick wetsuit or drysuit for comfortable snorkelling.

Low risk: Limited visibility

Visibility can vary dramatically with weather and plankton blooms; poor conditions may reduce visibility below 5m.

Low risk: Cold Water Temperature

Temperate Tasmanian waters remain cold year-round, typically 12–18°C, posing a risk of cold shock and hypothermia without adequate wetsuit protection.

Low risk: Rough Seas & Swell

Exposed to the Tasman Sea, the island can experience sudden swell and choppy conditions, particularly in winter.

Low risk: Rocky Shore Entry

No sandy beach; entry and exit are over slippery rocks and boulders, increasing risk of injury.

Low risk: Boat Traffic

The area is used by recreational and fishing vessels, posing a collision risk for snorkelers near the surface.

Low risk: Slippery & Sharp Rocks

Sharp encrusting barnacles and bull kelp on intertidal rocks present a slip and cut hazard when entering/exiting the water.