Diving and what I found underwater

I didn't realize we were going to another cenote, I was mostly thinking about food. But we arrived at a second one and filed out to pee behind a hut, then climb down a little ladder to the slipperiest mud I have ever slid upon and surfed our way to the water. There was one shaft of light tunneling from the ceiling through the water. It was impressive. We couldn't see much else until Raul brought one of those shiny windshield protectors and set it up to reflect into the cavern. Wow! I thought I didn't want to swim again (I was so hungry...) but within a minute or too I was jumping off the edge and totally absorbed. We took turns diving under with the flashlight to see what was under the ledges. I saw a white line running along a low wall and asked Raul what it was. He said it was the linea de la vida, the line of life, used by scuba divers to find their way out if it's dark or they are having trouble. He dove down to touch it and told me it was seven meters deep (21 ft.) He started to teach me how to dive deep. You have to blow your ears at certain depths and then return to the surface slowly and relaxed. When he put his hand above his head, he would just float up. So I put my face under, took increasingly deep breaths and dove under. I swan down to the line and then turned up and waited to start rising. I panicked at being so far down and shot up to the top. Raul told me that was bad and could be dangerous. I could tell he was right because I was really dizzy. I had to try it again so I started my breathing and dove down again, this time touching the line and reminding myself to relax and bouyancy would do the rest. I put one hand up and expected to rise. I didn't feel it so I put up the other one. I was being calm and patient, trying to just trust physics, but I wasn't going up, I was sinking further down! I looked up to find Raul and his hand was just above my head, I grabbed on and he pulled me slowly to the top. I was so surprised. I asked him what happened and he said "I looked down and there you were going away." He explained that differences in body composition can alter bouyancy and that I have negative floatation. So basically it is because I am buff! Hahaha. This is apparently great for scuba diving, but not so helpful for surfacing. After that he started to tell me about his ecotourism company and how he needs another person to work for him. And so opens another opportunity...