What game worlds did you have the most fun exploring?

I was discussing the concept of exploration within a game with a friend and what makes a game have "good" exploration. For me it has to do with the feel of the world as you travel it but most importantly rewarding the exploration properly. There are countless of modern open world or semi open world games with huge maps that amount to 15 story locations and 50 copy pasted points of interest with 5 different varieties and pretty much the same generic loot along the way.

This is where games like Fallout thrive. Despite having quite a few generic locations it usually always rewards exploration with something the player values: Unique weapons/items, Bobbleheads or skill books as well as unique quests and events. Stumbling into the alien ship or reaching tempeny tower on my own were one of the greatest feelings of exploration in gaming.

We continued discussing to the point where I was asked to name games where I had actual fun exploring around and to my surprise I could come up with very few:

- Fallout 3/4 and Oblivion/Skyrim

- Kenshi

- Hollow Knight

- Divinity Original sin II

What games do you remember that made you lose yourself in the world and enjoy the exploration aspect of the game?