A 5.8-magnitude quake struck Indonesia's Maluku province on Friday, the geophysics agency said.
The quake struck at 7:58 am (0058 GMT), 57 kilometres (35 miles) southwest of Ambon at a depth of just 10 km, the agency said.
No tsunami warning was issued.
"We felt no tremor here on land. The quake occurred on the sea," Ambon police officer Sumijo, who only uses one name, said.
Indonesia sits on the Pacific "Ring of Fire," where the meeting of continental plates causes high volcanic and seismic activity.