AUSTIN (KXAN) – As the temperature heats up, many Central Texans will head to the recently-filled Lake Travis to cool off. But, most people don’t realize the lake is also where a 40-year graveyard exists.

Over the past five years, 17 people have drowned in various parts of Lake Travis. Over the past several decades, another nine people have disappeared into the depths of Lake Travis, never to be seen again.

Among those still missing, is a couple whose boat turned up empty near Devil’s Hollow in 2003. William Crumpacker, a father camping with his two young sons, mysteriously disappeared during a late night swim in 1998. Four years before that, Jeffle Hughes was reported missing in 1994. Scott Wynne was wind surfing near Windy Point in 1989 when he vanished. In 1976, three people on a yacht were never seen again after they jumped into the water for an evening swim.

One of the nine still missing is Song Sok.

For Song, time on the lake with friends was the best way to spend a hot July day.

“It was the weekend that they all decided to take a mini vacation because they were working so hard,” Kha Sok, Song’s sister says.

Kha says her brother, a 20-year old UC Berkley computer science student, was interning in Dallas at a tech company the summer of 2014. Their group picked Lake Travis for a fun weekend away.

“We never thought of this before, we never thought he would come here and tragedy happen to him,” Kha says.

As the group was ending a full day of fun in the sun, Song jumped in near the VIP Marina (Volente area) for one last swim. His friends say he went under and never resurfaced.

Lake Travis, a reservoir formed in 1942, has the largest storage capacity of all the Highland Lakes. While the average depth is 62 feet when the lake is full, the deepest part of the lake (between Volente and Hudson Bend) goes to a depth of 210 feet.

Sgt. Michael Stroh with the Travis County Sheriff’s Office Special Ops team says Lake Travis is one of the most difficult places to search, even at the average depth. As one of the founding members of the Travis County Dive Team, Stroh is still surprised by what he sees in the murky waters of Lake Travis.

“It’s a dangerous lake if you’re not familiar with it because there are no sandy beaches here, it’s a very steep drop off,” says Stroh. “You can wade out into 2 feet of water… and step off a rock and then you’re going to be in 8 or 9 feet of water.”

Crews searching in the depths of Lake Travis. (KXAN Photo/Tom Rapp)

In the area around Starnes Island, where many party barges go and park, the water drops to more than 80 feet. Authorities say Pace Bend Park is also a high-risk spot because people like to jump off the cliffs into the lake and can hit the debris below.

Between dry spells and frequent floods, the lake level fluctuates, which creates even more hazards.

Lt. Jose Escribano says the “sometimes islands” that surfaced during the drought allowed new trees to sprout, but the new trees aren’t the only thing divers are worried about. “In the middle of this lake… there are pecan groves all the way down there.”

Divers tell us they expect drownings to increase this season with all area lakes full.

“[Drownings] are all preventable, all you have to do is wear a life jacket,” says Senior Deputy Alberto Luna.

During the search for Song, his family raised enough money to hire a private dive team from Florida State University, and even they came up empty-handed.

“They told us that it was one of the most hazardous dives, and they dive the Hudson [River]!” Lt. Escribano says. “They said diving in there with those trees, at those depths, is extremely hazardous.”

Song Sok, far right, with his mother and sisters. (Couresy: Sok Family)

In those hazardous depths is where divers think Song’s body may rest. The area where Song disappeared  has gone from 100 feet to nearly 140 feet in just a few short years, making it difficult for divers to locate his body.

“You can’t see anything. Even with the camera systems we have, the sonar we have, you can see certain obstacles, big obstacles, but the fact that he was so small and didn’t have a lot of body fat, he didn’t surface,” says Deputy Luna. “We’ll search as long as we possibly can to find you. And our divers try their best to recover the person for the family and everybody else and sometimes it’s very difficult.”

Song’s family still has an active Facebook page set up to create awareness about his disappearance. His family has still not lost hope that Song will one day resurface.