Imagine, if you will, that you're deep under the ocean. Not quite deep enough for it to be pure darkness though. There are still rays of light piercing the water around you. Marine life is abundant, as they go about their fishy lives, swimming around in this vast pool of water. Then you start to panic, realizing that you've been underwater this whole time without any scuba equipment because I made no mention of it. But then you realize "Wait, this is only an imagination!", so you kick back and relax on the sea floor (or at least as much one could with the restriction of salt water surrounding you).
It's dark blue, if you haven't caught on yet or if I did a shitty job of this.