They explore a bit

The next morning the Raven II continued down the river going deeper and deeper into the dense jungle.

By noon time they reached a fork in the river with one of the sides blocked by some type of dam made up of a number of logs.

It almost looked like the logs have been placed there on purpose to keep something out or in thought Dr. Stevens.

Their boat can't possibly make it through the dam but Dr. Stevens is very curious to see what is on the other side of the dam.

"Maybe we can climb over it or get around it." Dr. Stevens suggests as he is irritated that they can't get by the obstacle blocking his path.

"No I don't think so." Captain Xavier replies looking at the height of the massive dam in front of them.

"Damn it!" Dr. Stevens yelled frustrated he can't see what's on the other side of the logs.

"Maybe we can go under it." Billy suggests.

"Under it?" Sandy asks her brother.

"Yeah maybe we can dive under it just to see what's on the other side." he says, "I bet it doesn't go all the way to the bottom.

"You might be right..." Dr. Stevens said looking at the dam and the water.

"Lets get our scuba gear and check it out." suggested Sandy.

It was quickly decided that Sandy and Billy would get their diving gear on and take a quick look underneath the tree dam to see if there was anyway under it.

Billy quickly pulled off his shirt leaving him in just his swim trunks as the young man began to put on his diving gear.

Sandy pulled up her white T-shirt to reveal a very tiny white string bikini underneath. It left most of her voluptous 37DD-24-35 body on display for the four men to admire. The two small triangles of the top covered not much more than her nipples while the tiny thong bottom just barely covered her smooth pussy lips and left her backside nearly bare.

Dr. Steven's wished his lovely bride had chosen a more conservative bathing suit to wear on the expedition today but was grateful his wife was an excellent scuba diver.

The men watched as Sandy strapped a knife to her leg and then put her weightbelt on.

Young Axel quickly helped Sandy with her tank as he checked out her incredible, nearly naked, body dressed in the daring bikini.

A moment later Sandy and her brother where in the water and headed towards the river's bottom.

The water seemed unusually clear as Billy allowed his sister to take the lead and he enjoyed the view of her bikini clad body as she swam just ahead of him. The sight of her DD breasts jiggling in her bikini top and her firm ass cheeks flexing with every kick of her toned legs was impressive to the young man as he felt his dick get hard.

"Stop it." Billy reminded himself, "She's your sister for God's sake. Pay attention to your work."

The two explorers swam the length of the dam until they came across a passageway under the dam just as Billy had suspected.

Sandy led the way through the passageway as her brother followed.

As soon as they were on the other side they realized the river opened up into a wide channel and the two divers began to head to the surface to see what their new surroundings looked like.

Sandy's head broke the surface first as the busty blonde pulled the regulator from her mouth and said, "Wow."

Billy's eyes opened wide as he saw a huge temple built on the side of the river. It looked like it hadn't been used in a long, long time.

What do they do next?

Explore the temple, swim back to the boat or ????