6 Dennis Martin 

A 6-year-old boy named Dennis Martin mysteriously disappeared in the Great Smoky Mountains National Park in 1969, baffling the authorities. Martin had been in the middle of a game with his brother and two boys when he got separated from the group and vanished. Unfortunately, despite thousands of searchers showing up to look for him, no useful leads were ever found. 

The disappearance of Dennis Martin was perhaps one of the most baffling missing-person cases of its time. In 1969, a 6-year-old Martin was playing with his brother and two other boys inside the Great Smoky Mountains National Park, Tennessee, when he suddenly went missing.

While five adults watched and talked from nearby, the mischievous boys had hatched a plan to sneak up on them and give them a start. As part of this plan, little Martin had gone in one direction and the other three boys had gone in another. 

Sadly, that day, June 14, 1969, would be the last time any of them saw the child. A search soon ensued after his disappearance involving thousands of people. However, even months after scouring the area, no evidence was ever found. Finally, in September 1969, the search was officially called off and Martin was never found. (1, 2)

7 Thelma Melton 

On 25 September 1981, Thelma “Polly” Melton began a hike with two of her friends on the Deep Creek Trail in the Great Smoky Mountains National Park, Tennessee. An hour into the hike, Mrs. Melton overtook her friends and disappeared over a hill, never to be seen again. Later, many theories around her disappearance surfaced, some citing suicide as an explanation while others called it an accident.

Thelma “Polly” Melton was 58 years old when she disappeared in the Great Smoky Mountains National Park, Tennessee. She was accompanied by her husband and two friends but on the day of her disappearance, had decided to go on a hike with just her friends.  

About an hour into their hike on the Deep Creek Trail, Mrs. Melton suddenly picked up her pace and overtook her friends, walking past them over a small hill. But when her friends finally made it over the hill, she was nowhere to be seen.

Back at the trailer, her husband, too, had not seen her, prompting the trio to report her missing. Soon, more than a hundred people were looking for Mrs. Melton but failed to find any clues. 

The bizarre circumstances of her disappearance have led some to theorize that she may have deliberately run away from her family, while others believe it to have been an accident. (1, 2)

8 Floyd E. Roberts III

In 2016, Floyd E. Roberts III was on a hiking trip with a group of people when he went missing. They were hiking in a remote part of the Grand Canyon National Park, Arizona and Roberts decided to take a detour up a hill, agreeing to catch up with the others soon. However, he never showed up at their meeting spot and remains missing to this day. 

On 17 June 2016, Floyd E. Roberts III set out for a hike with his friend Ned Bryant and his friend’s daughter, Madeleine Bryant. The trio was part of a larger group hiking through the Grand Canyon National Park, Arizona. 

While hiking with the Bryants, Roberts took a slight detour around a hill, agreeing to meet them on the other side. However, when he did not show up as agreed, the Bryants retraced their steps but were unsuccessful in finding him. The next day, they were able to hike to an area with cellular reception and alert the authorities of Roberts’ disappearance. 

In no time, a search party with sniffer dogs and helicopters was combing the area for Roberts. Due to the temperature being very high that day, officials were also concerned about Roberts being severely dehydrated. Unfortunately, they were unable to find any leads to his whereabouts and he still remains missing. (1, 2)

9 Samuel “Sammy” Boehlke 

Samuel “Sammy” Boehlke, an 8-year-old boy with mild autism, went missing from Crater Lake National Park, Oregon in 2006. His father was the last person to have seen the child, as he ran across the road and climbed a rocky slope, completely disappearing from view. Due to his autism, Sammy was also scared of loud noises, which may have further impeded his rescue. 

The Crater Lake National Park, located in Oregon, is one of the oldest national parks in the US. In 2006, an 8-year-old boy named Samuel “Sammy” Boehlke went missing there while camping with his family. 

The young boy and his father, Kenneth Boehlke, had stopped to play a game of tag near the Cleetwood Cove parking lot. In the middle of his game, Sammy climbed up a cinder slope and refused to come back down. When his father chased him up the slope, the child thought that it was a game and continued to climb until he disappeared over the top, never to be seen again.

Although hundreds of rescuers helped look for the child, covering an area of 4,000 acres, no trace of him was ever found. The Boehlke’s believe that due to Sammy’s mild autism, he may have been spooked by the loud noises of the rescuers, ultimately impeding their search efforts. (1, 2)

10 Stacey Arras 

Stacey Arras was 14 years old at the time of her disappearance in 1981. She had been hiking with her father and a group of six other people inside the Yosemite National Park, California when she stopped to take photographs of a neighboring lake. That was the last time she was ever seen, and her case still remains unresolved. 

On 25 July 1981, a 14-year-old Stacey Arras had gone horseback riding with her father and six other people at the Yosemite National Park in California. A few hours into the ride, the group stopped at Sunrise High Camp where they would be staying for the night.

A bit later, Arras informed her father that she wanted to take a walk over to a boulder near the campsite and also take some pictures of the view. 

Although that was her final conversation with her father, the last person to spot her was another group member named Gerald Stuart who was sitting near the boulder at the time.

According to him, Arras was seen walking towards a lake nearby before she vanished. When she did not return after a while, Mr. Stuart got concerned and organized a search party. Unfortunately, the only thing they managed to find was the lens cap of Arras’ camera. (1, 2)