In his cruising guide to the Sunshine Coast, Bill Wolferstan explains the implications for boaters regarding the geological differences in the two Thormanby Islands.
South Thormanby is composed of volcanic rock. Perhaps the island itself is the tip of a long dead volcano would explain the numerous coves and indentations that line its coast that were formed when the lava flow hardened. Some are suitable for temporary anchorage (with attention paid to forecast winds), but care must be taken to avoid the many rocks scattered offshore.
North Thormanby is made up of glacially deposited sands, its coastline is generally smooth, and shallows extend a significant distance out into the Strait on all sides.
Buccaneer Bay, located between the two islands, is a popular destination for day trippers and cruisers. Mariners should be careful in their approach, however, keeping the Tattenham Ledge Buoy well to port as it marks the end of a reef that extends a significant distance out from Derby Point.
The beach encircling Buccaneer Bay has been called the most beautiful on the Sunshine Coast. Much of the shoreline is lined with vacation homes, but the land just to the north of the gap separating the two islands is a marine park. The gap shallows considerably at low tide, leaving a pool in the centre where bathers can play in water warmed by the sun. And it is almost always sunny here in the summer.
We have visited Buccaneer Bay a few times, but never stayed overnight. According to our Dreamspeaker cruising guide, however, while it is open to the northwest, it offers good protection from southeast winds.
Be aware that on summer weekends the bay is busy with small watercraft zooming in from Pender Harbour, Secret Cove, and other Sunshine Coast communities.
FYI: The Thormanby Islands were named after the winning horse in the 1860 Epsom Derby in England, and Buccaneer Bay was named after the horse that had been favoured to win the race but ended up placing sixth.