If you are frequently diving, spearfishing or snorkelling from a boat, then you need a flag indicating that people are in the water. A dive flag is obligatory for every diver and in many states and territories of Australia, it is required by law!
You want to make sure that it gets the attention of passing boat traffic, which accordingly has to adhere to speed limitations.
The flags are made from a strong and hard wearing rip-stop Denier with heavy duty stitching. They are 100% colour fast and UV resistant, so they can protect you and your dive buddies for the longest time.
