A father and his son died in a cave diving accident near the coast of Florida while trying out new diving equipment on Christmas Day, police said.

Darrin Spivey, 35, and his son Dillon Sanchez, 15, both drowned after attempting to dive down to Eagle's Nest Sink, a complex and challenging course of underwater caves in Hernando County, Fla., according to the Hernando Country sheriff's office.

Spivey's fiancée, Holly King, called the sheriff's office Wednesday afternoon after she couldn't reach Spivey, who took his son to Eagle's Nest so they could test out brand new diving gear.

When deputies arrived in the dark, a hunter told them that the last time he saw the divers was about 11:30 a.m. as they suited up for their dive, Denise Moloney, a sheriff's spokeswoman, said in a statement.

At 8:30 p.m., a certified underwater recovery diver discovered Spivey's body inside a cave 67 feet below the surface, Moloney said. Two additional recovery divers were sent into the caves and found Dillon's body 127 feet deep, Moloney said.

According to Floridacaves.com, Eagle's Nest is also known as the "Lost Sink." "This is an advanced dive. Do not take this lightly," the site warns.

The site plunges to 310 feet in some places, and divers who want to experience Eagle's Nest should have full cave diving certification, according to CaveAtlas.com.

Spivey was a certified diver, but not certified to dive in caves, and Dillon had neither certification, Moloney said.

NBC South Florida reported that a sign near the water reads, "Cave diving in this area is extremely dangerous — even life threatening!! Do not dive unless you are a certified cave diver!!"

Forensic technicians took pictures at the scene and collected the divers' equipment, which will be evaluated at a later time in the ongoing investigation, Moloney said.