What Covers Most of the Earth's surface?

Before Don came home from work yesterday, he called me and told me to be ready to "go see something." As usual, he wouldn't tell me what it was all about, so I got prepared for a trip to Home Depot (we're in the middle of renovating). When we were in the van he was dying to give me a clue. I wasn't biting at first, because his clues are absolutely no good to me in any of these "games." Not wanting to hurt his feelings, I said, "sure" so over the course of 15 minutes he gave me clues. One of them was, "it covers most of the earth's mass." I thought, "hugh" and didn't get it. We were inside the store before I guessed what my surprise was. It was 63 watercolour pencil crayons. Then, he asked if I had enough colours and he started to pick out the colours he knew I used a lot (Cool Carribean and other bright colours). We were outside when he said, if you guessed "water" as being what covered most of the earth's surface, you would have guessed watercolour pencil crayons. Isn't he funny? Boy, am I spoiled.