From GuildWiki

New Chests and buried treasure I have opened.

These were all Refilled by the Jan 19 Update. ( So possibility of opening each Twice)

Apparently they all reset roughly every month so can be opened multiple times!

[edit] Treasure Chests

• Mehtani Keys, southeast from Kodlonu Hamlet, in a shipwreck. (Map) x3
• Jahai Bluffs, near Acolyte of Balthazar. (Map) x3
• The Hidden City of Ahdashim, near the southeastern platform. (Map) x3
• The Sulfurous Wastes, near Alem the Unclean, inside Temple of the Monoliths. (Map) Twice
• Domain of Pain, near the southern edge of the River of Souls (north side of the southeastern bridge). (Map) Once (missed it before Update)
• Nightfallen Jahai, past the Shepherd of Dementia. (Map) Twice

[edit] Buried Treasure

• Issnur Isles, southeast from Beknur Harbor, near the troublesome flamingos. (Map) x3
• Arkjok Ward, on the small island in the northeast, right next to Jurani the Merchant. (Map) x3
• The Mirror of Lyss, small island to the south, near Shezel Slowreaper. (Map) x3
• The Ruptured Heart, near Shahin. (Map) Twice

[edit] Do Not Touch

• Bahdok Caverns, at the treasure trove near the southeastern corner. (Map) Twice
• Forum Highlands, near Commander Sadi-Belai. (Map) Twice