Shenzhen, a coastal city in South China's Guangdong Province, is witnessing the largest red ride of the year. At its peak, a 15-square-kilometer sea area covered parts of Yantian Port, Dameisha and Xiaomeisha.
Despite the temporary closure of Dameisha beach due to the red tide, the number of visitors swarming to the beach was high during the weekend.
A resident in Shenzhen said, "I felt sticky all over."
Another one said, "The red tide has made the water red."
Experts say the phenomenon is caused by recent heavy rains and high temperatures. They say the red tide was not toxic but could lead to allergic reactions for some people. It also could kill fish by depriving them of oxygen.
Guo Xiangyu, staff member, Oceanic Monitoring Station, Shenzhen, said, "The red tide at the Dapeng Bay is caused by a higher-than-normal concentration of microscopic algae. Studies show it's non-toxic."
Local authorities are collecting water samples from the most affected sea areas to keep a close eye on water quality.
Guo said, "The algae mainly exists in the Yantian District and Dameisha. The severity has been declining through the past three days according to our data."
Experts say that the red tide would dissipate depending on temperature levels, as well as wind speed and direction. Local government is now building a self-monitoring system on the sea to test water quality. It's expected to be put into use by the end of the year.