The acting secretary for Marine and Port Services in Tonga, Louisa Kefu, says her main concern now, after the grounding of a ferry off the Ha'apai group of islands, is for the navigation lights there.
The Pulupaki damaged the lights when it hit a reef at Pangai early yesterday morning.
It remains stuck on the reef but the 430 passengers have been ferried to shore and those travelling onto Vava'u have continued their journey on a second ship, the Olovaha.
Louisa Kefu says the Pulupaki was licenced to carry 400 passengers.
She says Marine and Port will conduct a preliminary investigation into the grounding, and this may lead to a Court of Marine Enquiry.
Miss Kefu says they have fears the lack of lights at Pangai will endanger other vessels.
"Our man at Ha'apai is looking over the navigational lights... that is our main concern now, to avoid another boat running aground on the reef because the navigational lights are off."