Solomon Islands Marine Search and Rescue division says 7 people are missing after being dropped off for a dive near Ramos Island in Malaita province.
But it says a second group of nine people, including four children, missing since Tuesday, were located alive and well earlier today.
The dive group was dropped off to dive about 4 kilometres northwest of Ramos Island.
But the division says that when the driver who dropped them returned to pick them up, the seven men were nowhere to be seen.
Marine Search and Rescue says it is asking people in the area to look out for the group and that it may request the help of the intervention force later.