According to family, 24-year-old Daniel Marks is an avid hiker. They say he goes away on camping trips often and always came back when he said he would.
But this time, he never returned.
Kauai is known for its breathtaking views of the Na Pali Coast. Many come to explore the lush valleys here.
That's what drew Daniel Marks in November 2005.
But when he failed to return, his mother, Patricia Marks knew something was wrong.
"Daniel travels a lot, he's also a very organized, very dependable young man and so since he didn't call me to say he wasn't coming home, I, right away, was quite concerned," said Patricia.
Patricia hired a team of professionals to search for Daniel. Friends and family flew to the island to help pass out fliers. All their efforts came up empty.
But while searching for her son, Patricia uncovered something else, other men who went missing on Kauai: 22-year-old Jesse Pinegar of Utah, 28-year-old Bradford Turek of Ohio and 34-year-old Piotr Drabik from Canada.
Although there are no apparent connections between the men, and no speculation they all vanished while on the Kalalau Trail, Patricia says there are some similarities.
"They're all physically fit, very well educated. All of them are caucasian, they're all very much interested in the environment and in nature."
But how can they just vanish? Patricia has a theory.
"I wanted to explore if there's some way to find out how the young men all decided to go to the island just in the event that they were lured to the island somehow."
Daniel's disappearance remains a mystery but for now, Patricia vows to continue what she started, that fateful day three years ago.
"Mostly I spend my time looking for Daniel and praying for him."