The Coast Guard now prohibits all vessels from getting closer than 984 feet from where Kilauea volcano's lava oozes into the sea.
The Hawai'i County Fire Department reports four people were transported by medics to the Hilo Medical Center by ambulance, nine others went to the hospital in private vehicles and ten people were treated on the scene for minor soft tissue injuries and burns. It's unclear the total number of people on the boat. Eyewitness video footage from a nearby vessel showed a towering cloud of steam and ash billowing into the sky, punctuated by the glow of red-hot embers and flashes of lightning.
On Sunday, the USGS reported that the "now connected to the main flow front by a strip of lava".
The lava has covered more than 11 square miles (28 square kilometers) of land, vaporized the state's largest freshwater lake and filled an entire ocean bay, turning it into a mile (1.6 kilometers) of burnt, rocky ground.
The U.S. Geological Survey (USGS) discovered the formation of an island a few meters from mainland during a routine flyover on July 13.
Several lobes of lava from fissure 8 at Kilauea volcano entered the ocean along the southwestern edge of the entry on Wednesday in Puna, Hawaii island.
The agency said the explosion caused an increase in the lava flow, threatening homes in the Nohea neighbourhood.