Hi there
In my country, you can join the scuba- diving and snorkeling in Nha Trang or Phu Quoc. Let's me introduce you these places

Nha Trang lies in a beautiful bay on the south central coast of Vietnam.With white sandy beaches as well as nearby islands with clear turquoise waters, Nha Trang is also known as one of the best places in Vietnam for excellent fishing, snorkeling and scuba diving. Boat trips are also a real highlight of Nha Trang.

Phu Quoc is also called the Emerald Island because of its natural treasures and infinite tourism potential. There's plenty of strips of sand worth exploring -- Bai Thom on the northeast and Bai Dai on the northwest are both fine beaches and clear blue sea with Long Beach, Bai Sao, Beach Bai Vong; all is ideal for picnics, paddling, snorkeling or fishing.