Having made the decision to make this his base he made his way back towards the cliff face that butted up to the mountain. As he got closer he noticed a crack in the cliff face and went over to investigate it. He found a cave of sorts whose entrance was at an angle, so the opening was unable to be seen unless a person was walking along the cliff face.
Rosario used a match to light a candle and tied it to his spear tip, then with his spear at the ready in front of him Rosario began making his way into the cave. It was pretty tight on the sides ranging from a foot and a half wide at the narrowest to three feet at the widest spots. The roof of the cave stayed around eight to ten feet from the floor so thankfully he didn't have to crouch. He spent a little squeezing through the tight rocky corridor when he finally heard what sounded like dripping water ahead of him.
Continuing to work his way through the narrow confines he finally made his way into an open cavern. Surprisingly he didn't need the candle any more as there were what looked to be veins of a golden metal crawling over the walls, ceiling, and ground. The golden metal gave off a soft glow, illuminating the cavern he was now standing in. He seemed to be standing on a shore of sorts as dominating the entire cavern in front of him was a body of liquid. It was definitely not water as the liquid was a mix of swirling black and gold colors. It looked thicker than water too, it didn't seem to flow as well but had a super salinized look to it. The dry ground he stood on was probably spanned forty feet along the cavern wall and around twenty feet into the cavern before it met the strange underground pool.
The cave spanned to either side of him by about fifty feet to the right and seventy feet to the left. The cavern was in a rough football shape with the side he was on flatter than the point he could see the cave came to on the other side of the pool that was close to three hundred feet away.
Wanting to see how deep the pool was Rosario walked carefully to the edge of the pool, there was about a six inch drop off from the ground he was on to the swirling liquid below. Crouching down and observing the mesmerizing liquid closely he saw as the gold swirls moved about the water but what he hadn't noticed earlier but could see clearer now was accompanying the golden swirls were pitch black swirls that entangled themselves with the golden ones. Watching them move about in the liquid it reminded him of the Yin and Yang symbol from earth.
Looking to see how deep the pool was Rosario tested putting his spear tip into the liquid, getting no reaction he submersed the spear till the unknown liquid reached the wooden shaft. Just as there was a lack of reaction when the metal of the spear head touched, there was also no reaction when the wood touched the liquid. Deeming it safe for now Rosario slowly lowered the spear into the liquid till he was almost tipping forward into the pool. Deciding for stability's sake he laid down on his stomach with his head and upper arms over the edge so he could lower his spear as far as possible to figure out the depth of the pool.
The entire spear was able to be submerged and only the part of the spear shaft that he was holding was not surrounded by liquid. Not thinking too clearly he pushed his arm down into the liquid while holding the spear, rationalizing doing so because both the metal and the wood had no reactions when they came into contact with the strange liquid. It was a bad idea.
Right as his hand submerged, it felt as if thousands of needles had pierced through his hand at once. Shouting out and unconsciously storing the spear away Rosario flinched trying to pull his hand from the liquid as quickly as possible to alleviate the pain. To his misfortune he hadn't noticed that where he was laying looking at the liquid was actually a shelf of rock that had been eroded by the pool over the years. When he flinched and tried pushing himself up and away two feet of the ledge that his upper body rested upon broke from under him and plunged into the swilling pool below. Of course, with his whole upper body being supported by that piece of rock Rosario fell face first into the gold and black vortex of colors before him. A short yell was heard before his body was fully submerged.
Rosario plunged face first into the liquid and as each part of his body was introduced to contact with the pool he felt as if thousands of needles were stabbing him all over is body. He was in so much pain he couldn't even flail about, his body seized up as if he was being electrocuted. The pain was so unbearable that Rosario barely had enough time to absolutely regret his decision before he passed out from the pain, fully knowing this was the end for him.
After the shelves collapsed into the gold and black pool along with Rosarios short shout and headfirst fall in, the disturbed mystery liquid calmed within minutes. Had someone walked in just a few minutes after Rosarios perilous swim that person wouldn't even know that there had been a shelf of rock let alone a human falling in. Days passed as the underground cavern remained in a calm stasis with just a little drop of water falling from a stalactite on the cavern's ceiling.
Rosarios conscious came slowly back as he was hearing an incessant ticking and beeping sound. As he slowly regained his consciousness he was very groggy, not knowing what was going on around him. Not realizing his body was suspended he tried sitting up and he was immediately plunged into water. Choking and sputtering Rosario flailed about trying to right himself or grab onto anything. Finally, after a minute of panicking he managed to calm down enough to slowly tread water and catch his breath. He looked around and noticed he was still in the cavern that he last remembered before the worst pain he had ever felt had assailed him.
Remembering all the pain was because of the water that he was currently treading in, he freaked out again until the rational part of his bran told him that he had been in the water since waking up and he hadn't felt any pain now.
Still, not wanting to experience that again he looked around to find the ledge he had entered on and was able to see it about 50 feet to his left. Swimming over to it he climbed out of the water and moved as close to the cave wall as possible as he leaned his back on the wall trying to figure out what was going on.