Warden's Waterfall

Climb high and discover a giant nether portal just over the mtn spawn. Below there is a city with 3 blacksmiths.

Head east and there is a single block waterfall. This leads to easy access diamonds located around two ancient cities.

After you get your 18 diamonds keep going down the river and at the lava it is a t intersection to two ancient cities

See video for diamond speed run.

This seed is the perfect forever world.