Two Japanese teenagers found dead in Lake McKenzie on Queensland's Fraser Island had been on a public tour of the popular tourist destination with 29 other people.
Questions are now being asked about how the boys, both aged 16, drowned in what has been described as "a calm lake in the middle of an island" by the local mayor.
The pair were discovered in the water at 8.20am on Saturday after they were reported missing about 5pm on Friday from a tour run by SeaLink Travel Group.
Standard practice to allow tourists free time
Jeff Ellison, the company's chief executive, told reporters in Hervey Bay on Sunday that it was standard for the tour bus to stop at the lake where passengers were briefed before being let off for some free time.
"My understanding is that at the end of that time, five o'clock, there were two short and the tour guide identified that it was two of this group," Mr Ellison said.
"He immediately commenced a search of the area, the toilets in the area, and as that didn't find anything they raised the alarm to our office here."
Police were called and staff sent from the nearby Kingfisher Bay Resort to help find the boys, who were visiting with a larger group from Kanagawa University High School in Yokohama.
It was understood the teens had not been left behind at the lake and their group reported them missing from an area nearby.
The boys were not with their families on the tour, Mr Ellison said.
The rest of the students on the tour stayed at the site while buses were sent to bring back the other passengers.
Tour company defends protocol
"We've looked at our protocol and we're very comfortable with that ... but it does seem a terrible, unfortunate accident," Mr Ellison said.
The tour group left the island on Saturday afternoon to return to Brisbane, where parents of the boys are reportedly travelling to on Sunday.
"It's very unfortunate that this has happened, we are very sorry," Kanagawa University High School principal Hisashi Kikuchi said.
"The two students were very bright and energetic, I think everyone liked them very much."
A file image of K'gari/Fraser Island. Source: Supplied
Tourists advised to 'know your abilities' around water
Inspector Tony Clowes said he did not know if the boys could swim and that their deaths were tragic.
"Know your abilities, be aware that if you are entering water there is some inherent risk entering waterways in this country," he said on Saturday.
Police are preparing a report for the coroner and are in contact with the Japanese consulate.
Inspector Clowes said the details surrounding how the children were supervised would be investigated.
The public need to be aware of their swimming abilities before entering Australian waters, Clowes added.
"Be aware that if you are entering water there is some inherent risk with entering waterways in this country," he said
Clowes said families of the boys have been notified and authorities were working with the Japanese consulate to provide support.
Community in shock: Mayor
Fraser Coast Mayor George Seymour told the ABC the deaths had shocked the community.
"Lake McKenzie is the postcard-perfect image of Fraser Island - it's where all the tourists go," Mr Seymour said.
"It's really unimaginable how somebody, let alone two people, could drown there.
"It's a calm lake in the middle of an island ... whatever has happened is highly unusual."
