Follow CBSPHILLY Facebook | Twitter

PHILADELPHIA (CBS) — The rescue effort to save a soccer team trapped in a Thaliand Cave has progressed as eight boys, one by one, have been able to tether to Navy SEAL divers, to make the two-and-a-half-mile trek and dive out the flooded cave.

Four more boys and the team coach still need to be rescued.

Credit: (CBS3)

The dive necessary for the rescue was described by a Philadelphia-based diver as “on a scale of one to ten, this is a 15.”

David Barnes of Scubadelphia has been scuba diving and cave diving for more than 20 years. He’s also dive instructor in for the business in Mayfair.

“This is way different than anything we have ever seen before,” said Barnes.

In looking at a map of the cave in Thailand, Barnes explained exactly why the Thailand rescue and dive is so different and so dangerous.

“It’s taking them five, six, seven hours to get out of this, and most dives are 30, 40, 50 minutes to an hour,” said Barnes.

Not only is the Thailand cave dive at least 5 times as long as some of the most adventurous cave dives, the Thai cave has extremely narrow pathways that require a diver to make specific maneuver to get through tight spaces.

5th Boy Rescued From Cave In Thailand

Credit: CBS3

In Thailand, this maneuver is being done during the rescue in pitch-black darkness.

“You are doing everything by feel. Those guys are trained for that,” Barnes added.

The boys being rescued are not though.

In the cave, over the span of a few days, they were given a crash course on diving.

Barnes says that makes them likely to panic at some point during the dangerous dive.

Credit: (CBS3)

To prevent that, it’s likely each boy is wearing a specific air mask that allows the seal divers to communicate and even calm them down, if necessary.

Divers say the Thai dive and rescue is something that will go in the history books for divers around the world and rescuers will  learn from for years to come.