if you meaqn by sea chart then all of them are in the ocean temple you can not obtain them all at once.
on the island
In the Northeaster sea.
go to the temple of courage
temple of the ocean king
close the lid
its the north eastern part of the south east map
Go to the area on the map where you transferred the crest.
in the temple of the ocean king basement 11 or 10 I think
Whatever path you draw on your map.
in the south western sea, in the top right corner of the map
There are many uncharted islands, at least one per map.
you use it to find beard beards treashure.