Sea of Prickles - Robin Freeman - Bog

Escaping the clutches of the sorcerer in his island hideaway, Avalon and his three female companions set sail on Ghost Runner. On their long voyage they get sucked into a giant whirlpool half a mile wide at its gaping mouth during a severe storm, are attacked by fierce pirates, and eventually discover an unchartered, uninhabited archipelago where they make the tropical paradise their home for six blissful months while the hurricane season rages all around them.
Whilst there they find a derelict town on one of the coral atolls and in a hidden chamber beneath the ruins of an ancient temple Avalon unearths a treasure beyond value. On the wall of the secret chamber they also find a pictorial history of the island's inhabitants that reveals a startling fact about the people that had been captured by slavers three decades ago. Avalon is told by a Spirit Being that he is to return the treasure to the rightful owners who are enslaved in a land thousands of miles to the northwest. When they finally arrive at their destination their search for the whereabouts of the slaves leads them into extreme danger.