A day after Bangkok's deadly bomb attack there has been a second explosion in the capital, this time at a ferry pier, but this time no one was hurt, police say.

Police Senior Sgt Maj Worapong Boonthawee says an explosive device was thrown from the Taksin Bridge this afternoon and blew up at Sathorn Pier after falling into the Chao Phraya River below.

"There is no injury," he says.

Security camera footage shows a sudden blast of water dousing people on a walkway at the pier, as bystanders ran for safety.

Yesterday’s attack killed at least 21 people, including foreigners, and scores were injured.