Stuck in a Nightmare

I laugh in delight as I dive off the pier into the lake at Camp Half-Blood. Even though I can breathe under water I hold my breath as I hit the water, swimming deeper and deeper, the coolness bliss after the stifling heat of the day. As I'm swimming there is an uncomfortable pressure on my chest and the further down I swim the worse it gets until eventually it's almost unbearable and then my ears pop. No, that can't be right, I have swum way deeper than I am now without ever being affected by the pressure at all. I will the water to push me back to the surface, but nothing happens. I try call one of the hippocampus telepathically to help me, no answer. Now I am really starting to get worried. I am tempted to not even try breath because I'm terrified it won't work, but my lungs are aching, crying for me to breath. I close my eyes and try take a breathe only to have water fly up my nose. My heart starts beating wildly in my chest as I choke on the water, the water that was once my refuge but now it appears may be my doom. My vision is going fuzzy around the edges, I know I have to get to the surface, I need air, but already I am growing weaker and weaker. I can feel my strength ebbing away with each feeble kick of my legs until eventually I can't even summon enough strength to move my legs. I just float there near the bottom of the lake, the surface glittering far above me as my heart slows and everything goes black...