Yes, a towable tube is often called a sea biscuit or ski tube.
All three terms usually refer to the same type of inflatable water toy that is towed behind a boat for fun on the lake, river, or sea. The main difference is simply what people call it.
- Towable tube = the general product name
- Sea biscuit = common everyday term in NZ/Australia
- Ski tube= another common local term, especially when used behind a ski boat
So if you’re shopping for a sea biscuit, ski tube, or towable tube, you’re generally looking at the same kind of product.