Well lets see... There's the enjoyment of watching the fish and corals move in the current (I like to do this after a stressful day at work), there's watching corals grow from small frags into larger pieces and hopefully someday mother colonies, having our two Lysmata amboinensis crawl up my arm every time I put my hand in the tank, but most of all I enjoy the glowing ear to ear smile of children who see the tank for first time and hearing things like "wow, I want to be a scuba diver; look at the pretty tree's, etc." priceless.