Ocean monuments are naturally generated structures as of version 0.16.0 (and 0.15.9 alpha) of Minecraft Pocket Edition. As they are generated on the depths of the ocean it’s quite difficult to get a good idea of what one actually looks like. However, with this map you can explore both the outside and the inside very thoroughly. The creator used this seed which we posted earlier this week and then dried out the entire structure
IMPORTANT: This map will only work for 0.15.9 alpha and 0.16.0+ as it uses a world seed with an ocean monument which got blocks which only work for those versions.