Exploration mods

[OniyaMCD]

The first place I would start is https://minecraft.curseforge.com/mc-mods. You can then search for mods based on your preferences, but I recommend looking in the Adventure and RPG section for your needs. After that, I would recommend mods such as Mystcraft (magic based dimension exploration), RFTools (tech based dimension exploration) Roguelike Dungeons (overworld dungeon crawling), Astral Sorcery (magic based mod based on night time and searching for ruins in the overworld) Forestry / Bees (has a person searching the overworld for bee hives), Twilight Forest (dimension mod with insanely hard titans to fight, think Gaea and the titans), Biomes o Plenty (pretty world gen to explore), Abyssalcraft (like Astral Sorcery but demon based), Galacticraft (space exploration), and so many more. It really just depends on what type of exploration you want to do.

Yes, I could probably go in and do a global search. There's one thing that doesn't provide me with, and that's the personal experience of 'why would you recommend this mod'. I suppose I could make a guess based on number of downloads, but that would risk overlooking some amazing mod that just doesn't have the 'word of mouth' thing going for it.

 

[SomeRandomPetey]

Personally, I'd recommend a couple mods:
Recurrent Complex (1.7.10 and 1.12)
Roguelike Dungeons (1.7.10 and 1.12)
Biomes O' Plenty (1.7.10 and 1.12) OR Biome Bundle (1.12)
The Twilight Forest (1.7.10 and 1.12)
The Betweenlands (1.7.10 and 1.12)
Atum (1.7.10)
Advent of Ascension (1.7.10)
The Erebus (1.7.10 and 1.12)

These are all mods based around exploration and adventure.

You do not need all of these mods, these are mods I just recommend looking at.