awsome,be sure to pick your tour operator carfully,as some run extreme cattle boats!may is the best time of year to go,white sharks are at their most abundance.
Facts about shark ally,by dyer island

• It is in South Africa
• shark ally,by dyer island is in the Atlantic (African coastal).
• The typical depth is 0-10 Metres 0-30 Feet.
• The typical visibility is 3-10 Metres 10-30 Feet.