"You get what you pay for," Ms Wilkinson told the Sydney Morning Herald.
They said they paid $175 each for the four day boat tour.
"As soon as we had bought the ticket, I said to Tony I think we have picked the wrong boat."
Ms Wilkinson said problems began when the boat hit a coral reef on Thursday August 14.
It was early Saturday morning, while on their way to Komodo Island, that the ship began to sink.
"The engine stopped because the hull was flooded ... The weakened hull must have given, so now the boat had a hole, no bilge pump, and a hull full of water. It was 90 per cent sank within half an hour," Ms Wilkinson told the paper.
"The crew were hopeless. They accepted their fate and that was that."
Ms Wilkinson told the Sydney Morning Herald that another boat came close by, but they had no flares to attract it.
"Our Indonesian guide got a broomstick with a rag on the end and some kero, and had a live flame he was waving around. It was pretty frightening because by that stage there was fuel all through the water."
Ms Wilkinson said six tourists then got into the life boat, with the remaining 19 passengers hanging on to the dinghy.
She told the Sydney Morning Herald they decided to wait with the ferry, which was still only partially submerged.
"We were slowly sinking and it was getting dangerous. Waves were washing us off the roof, we were climbing back on, being washed off again," she said.
On Saturday Ms Wilkinson was one of five people who swam towards Sangeang Island, an active volcano, which was in sight.
She swam for six and a half hours, and arrived at the island at dusk.
Mr Lawton stayed with the dinghy and tried to get the 20 people to kick it towards the island, the Sydney Morning Herald reported.
He later also swam to the beach and ended up 10 kilometres further up the beach than Ms Wilkinson.
Ms Wilkinson was rescued by a five-star dive boat, named the Mermaid Liveaboard, and Mr Lawton was rescued by local fishermen. The couple were reunited in Bima.
Two tourists from Spain remain missing, and Mr Lawton said they swam to the island about 30 minutes after he did.
Ms Wilkinson said she now wants to warn people about the safety of these trips.
"Take your own personal locator beacon; check they have got life jackets, communicators if something goes wrong."