West of the mountain and the mines is a giant tree and a tunnel full of water beneath it. You can spend a decent amount of time draining the water out from under the tree and get through it. There, you'll find a scroll which is generally useless. Scaling the tree, you'll find an egg in a nest on a branch, staying in the nest for an extended period of time will summon acid spitting, flying eyes that can easily kill you.

There are many ways to get above the mountain. The easiest way is to go through the mines and head east until you find a point where you can blast your way through with a bomb, or where there is a hole you can exit through. Another way is to get a Polymorphine or Chaotic Polymorphine flask and use it to become a flying sheep, this is the most useful way. You can also restart until you have a high enough mound of dirt in front of the mines entrance (very low chance).
From there, the mountain's peak is very low and covered in snow, above it is a flying island. There is no way to get to the flying island without having first gone into the mines or headed east and gotten lucky, see below. If you have the Polymorphine or Chaotic Polymorphine, you can turn into a sheep again and fly up and around the island, using the default wand to blast your way down to the orb and scroll there. If you have gone through a Portal Deeper and have the "Strong Levitation" perk or "Low Gravity" perk, you can scale back up from the East, under the super dense rock area (and its hidden area) from the Frozen Depths cavern. The altar on this flying island can be used to turn scrolls into items (I think just gold at this moment).

There is a small ocean (more of a lake) east of the mountain after some more grasslands. Beyond this, you'll find the desert which stretches on for quite a while and has some interesting scenery, but little to interact with. If you go further, you'll find the Pyramid, which to get inside of you'll need a bomb, chainsaw, or drill spell and have to tunnel your way through the seal (you may be able to tunnel straight through the Pyramid's material, but I haven't gotten a drill spell to try it yet). On top of the pyramid is an orb and a scroll. Inside the pyramid are intensely powerful enemies from later areas of the game that can easily drop your health to 0.

If you continue on past the pyramid, you'll come to a sheer cliff, made out of weird shapes which give an easy foothold to climb its face. Upon reaching the top, you're greeted with the message, "Entered ???" and nothing else. At that point, if you explore further into the dark of this area, you'll find another sheer face like the one you just scaled and if you scale this, you can fly onto a rhombus of brickwork and stone in the center. If you're good at kick, you can blow a hole into the stone top and drop another 1 (or 2) onto it to get inside. Otherwise, acid trail, acid, drill, or chainsaw can get you inside with a little work. It's almost not worth it as only a perk is held within.

If you enter the mines and head east, you'll eventually find super dense rock and if you keep going down until you reach the level of depth at which there are the portals deeper, you'll find a hill that leads to a scroll talking about medicine which "cures all ills" next to a lava lake. It's a little on the nose. However, if you pull out your water flask and use right click to build yourself a bridge across, you can find a massive gorge and more super dense stone. Flying across this gorge will take you to a secret room with a scroll and an orb. If you drop down the gorge and head west, you'll find yourself in the Frozen Depths biome. It is not recommended that you challenge the Frozen Depths with default wands, so it's best to traverse the mines and caverns below it and use this route to go back to the surface when you want to.

At a certain point in one of my runs, a portal deeper's brickwork had a hole next to it, which I thought was a glitch. When exploring deeper, however, I found myself with the message "Entered The Vault" and surrounded by metal and machines and powerful enemies. However, there were powerful spells and wands (3 rows of spells initial to one wand I found) to match. I don't know if this is true underneath every portal deeper, but if you happen to have an acid trail spell or a drill spell, searching underneath a portal deeper may hold great treasures for your run, granted you don't die while in the vault.

I heard that there was an orb on top of the tree, and another secret under the lava of the lava lake, but I haven't gotten a chance to confirm or deny that these exist. For now, this is all of the secrets I've documented. In my next update, I'll go to the top of the tree, under the lava lake, around the
eastern edge of the world and add pictures. This was my first guide and I hope you find something useful from it.