Transport Between Biomes: Portals?

I'd love to see something that would allow easy transport across thousands of blocks. I've found a couple of biomes in my world that I want to explore properly but it can take two Minecraft days to get there by boat. I think if there was some way to build portals or similar between places in the Overworld it would mean you could build bases in multiple biomes without losing them or having to travel thousands of blocks just because you left something at your main base. I'm talking when a rail system or similar would be virtually impossible.