Trong Mai is situated on the south-west side of Ha Long Bay, 5 km from the tourist wharf near to Ðinh Huong Islet. In a somewhat large expanse of open sea, the island seems to grow up from the bottom of the deep emerald waters.

At sunset, the island with the height of over 10 m is bright red and in a somewhat tottery position. Their tiny legs support heavy bodies, and it appears that one strong wave could throw the two stone blocks into the sea. However, hundreds of millions of years have passed, and the Trống Mái is still there. The image of the island is the logo of Hạ Long Bay and Vietnam Tourism.