Basically the way I did this was
- Play as America
-Custom game
-settler
-huge map
-two leaders
-no city states
-no barbarians
-no turn limit
-no score victory
- any map with alot of coastline.
-arid world
-new world
You can start in any age i did information age
Basically you want to spam anything that helps you build Seaside Resorts ASAP on lvl 4 land on the coast
once you do that and build up your culture the achievement will pop