Submarine tours taking visitors down into the underwater worlds off the coast of Vietnam have been launched as the country seeks to ramp up international visits again after restrictions during the pandemic. Tour operators at the coastal city of Nha Trang say visitors can admire the seabed and see a wide variety of aquatic life, coral reefs and the wreck of a 50-metre-long shipwreck during a 30-minute dive in Nha Trang Bay. The 24-seater transparent-walled tourist submarine named DeepView24 opened to visitors in April at Hon Tre Island, a few days before the 47th anniversary of the end of the V…