Sea environment ambassador Dao Dang Cong Trung and 20 members of the Thanh Khe swimming club gathered at a rocky spot in Son Tra Peninsula to collect trash from the seabed.
The volunteers were experienced in underwater activities and included swimming coaches for local schools and professional athletes.
First they collected large amounts of trash from the surface, mostly plastic bags and fast food containers left behind by visitors.
Then they dived to collect trash from among the coral reefs, taking caution not to accidentally damage them.
Since the trash could be hidden in all nooks and crannies, the volunteers had to pay close attention to their work.
In fact, several reefs in the area have already been damaged by various factors including tourists stomping on them while diving.
Some of the volunteers found beer cans buried in the sand at a depth of three meters.
The swimming club of Thanh Khe District has collected trash from the seabed around six times.
Phan Thanh Tin, 45, a teacher at the Da Nang Sports University and head of the swimming club, said the club would try to organize such clean-ups every month.
Sometimes volunteers would have to use their own feet to pick up the trash, as diving too deep could be dangerous if they're not used to equalizing pressure.
Volunteers bring bags with them to collect more trash before having to swim back to shore.
It would take corals about a year to grow a few centimeters, so they would take a long time to recover from damages, experts said.
Nguyen Ai Viet, 46, and his children Nguyen Hai Duong, 6th grader and Nguyen Hai Dang, 12th grader have been collecting trash off the Da Nang sea floor for the third time.
He said the activity has taught his children to throw trash in their proper places.
