The Coast Guard launched an investigation after a watchman spotted a suspicious diver near a Coast Guard boat overnight.
That diver was never found, but the Coast Guard has called off its search.
And they say the harbor is safe.
"We were told they're checking in case of a terrorist," said Yusaku Kokubu.
Kokubu is one of the college students on board the ship. It arrived in Honolulu last weekend.
The Coast Guard searched for hours from land, water, and the air to make sure the harbor was safe.
Mario Dalfonso is a crew member on another ship that was searched.
"They checked the dive lockers, seeing if any gear was wet," said Dalfonso.
In the end, the extensive search turned up nothing.
A number of agencies were involved including Honolulu Police and the Joint Terrorism Task Force.
Tonk, any info on this?