Had my first serious spelunk today. Found a small cave stuffed full of creepers and spiders right under our house. Cleared it out and found connecting tunnels. Ended up opening up in lots of directions, difficult to keep track of and easy to get lost in - some looping back on themselves. Definitely need to work on my navigation.
My son was really scared by it, telling me to stop all the time. Not sure if it was the dark caves, or the worry that i'd die and lose the diamond sword.
I was doing well until one misstep made me fall down a pit, and I came face to face with my first ever giant fucking slime. So I shot it with my bow. It then split into smaller ones which I also shot, ending up with a bunch of little ones. I vaguely remembered reading that they can't hurt you when they are small, so I relaxed a little. And they pushed me into a lava lake and I died, taking all my inventory down with me
Eventually went back and cleared it out, and came back with a few diamond and a decent amount of iron. Still barely enough to cover what i'd lost, but it was a lot of fun.