The lava punctured the boat's roof and it returned to Wailoa Harbor, the fire department said.
The roof of the boat after an explosion sent lava flying onto it Monday morning in Hawaii.
Hilo Medical Center confirmed 13 passengers were treated at the hospital, and another 10 passengers with superficial injuries were treated on arrival at Wailoa Harbor.
Of the 13 injured passengers, four were taken by ambulance to Hilo Medical Center, according to the Hawaii County Fire Department.
One woman in her 20s was in serious condition with a fractured femur, the fire department said. Three passengers were in stable condition.
The lava bomb, or flying chunk of molten rock, left a large hole in the boat's roof, the fire department said. A railing was also damaged.