I'm playing in 1.12, with mods. I absolutely HATE (that word is not strong enough!) the ridiculous vanilla Pangaea world of a single big continent with lots of lakes. I want a world of oceans, with continents and islands randomly generated and all separated by ocean/ deep ocean. I explore these worlds by naval ships, airships, and airplanes, and will often head out as much as 50 km from the world spawn in search of the perfect place to build.
Can this be done in 1.12 using the custom world type? If not, does anyone know of any mods currently available for 1.12 that can pull this off? ClimateControl/ GeographiCraft hasn't yet been updated to 1.12 from 1.11.2 and I don't know of any other mods personally that can do anything like this.
recent versions of Biomes o Plenty have included the ability to customize BoP worldgen. You can choose from three basic types--archipelago (lots of islands), continents (what you're asking for), and whatever you would call a large-landmass world. You can further fine tune customizing options such as climate zones, biome sizes, and so forth.