The discovery of four teenagers alive and well after going missing overnight in waters off Victoria's Mornington Peninsula has been hailed a "Christmas miracle" by police.
The two 18-year-old men and two women, 18 and 19, were found on Swan Island off the Bellarine Peninsula about 9am on Tuesday after they got caught in strong easterly winds and spent the night drifting in a choppy Port Phillip Bay.
The group set off on two inflatable paddle boards on Monday evening from Rosebud Foreshore before drifting into the middle of the bay, and ultimately ending up about 30 kilometres away.
Cold and disoriented when they washed up about 2am on Tuesday, they found shelter in a hut.
Once the sun rose, they wandered Swan Island before being found by security officers.
They were taken to Geelong Hospital in stable conditions with no obvious injuries, Ambulance Victoria said.
Island security and military personnel ultimately alerted police.
"All too often, these things usually end in tragedy," Acting Inspector Ian Pregnell told Melbourne radio 3AW.
"This is, one might say, a Christmas miracle."
Jack Shi, father of one of the teens, told Nine News of his and the other parents' relief.
"We're very, very happy about that. It's huge, huge relief. We were very desperate," he said.
Swan Island is a military training base on one side and Queenscliff Golf Club is on the other.
It has a long history of military use and a fort was originally established on the island to protect the entrance to Port Phillip Bay from potential Russian invasion in the 1870s.
During World War I it was used as a depot for naval mines before becoming a training base following World War II.
Winds in the area were easterly and southeasterly on Monday evening and overnight, and 20-30km/h, according to the Bureau of Meteorology
However at South Channel Island - a close observation point - they reached 30-40km/h. The highest gust recorded was 52km/h about 4am, although the observation point is particularly exposed, duty forecaster Ilana Cherny told AAP.
The group's belongings including phones and IDs were found on the beach by a passerby about 8pm on Monday, triggering the search.
The effort was called off about 4am due to deteriorating conditions but resumed at first light.
A man who said he was the father of one of the boys told Seven's Sunrise the teens had just completed their final school exams and went to Rosebud for an end-of-year celebration.
The successful rescue came a day after a couple was found safe and well in the Grampians in Victoria's west after their car became bogged at the weekend.
