I had a lucid dream, I fell in water and couldn't swim to surface...my body was so... Heavy I just kept sinking.... Down deep into this endless abyss.
I yelled for someone to help me.. Then all a sudden I was at the other end of abyss, and there where these figures with bows shooting arrows at me ...
I had to tell them stop I'm on your side.
Thy stoped and said. "She's three thing's. Then I woke up.
Are you asking why you lost control? Or are you asking for someone to interpret your dream? If it is the former...well...
I would assume that you ran out of "Lucidity". Or you lacked sufficient "Lucidity".
If you had sufficient Lucidity, you would be able to will yourself to swim, will yourself to be lighter than air, perhaps even rapidly changing your surrounding environment at will. Removing the water, Destroying the sun etc.
I wouldn't worry too much about it though. The levels of one's lucidity comes in waves, and can vary rather greatly. Losing lucidity and control in a dream is not uncommon among Lucid Dreamers.
Usually it means something is dragging you down in your life. Lucidity could be it too but usually it problems in your life that you can't change. That is why it's dragging you down. Try to pinpoint it and you may be able to stop this from happening.