It is Day 3 of the Lost Riches event in Genshin Impact, and Treasure Area Six will be available to explore for those who have worked through the five previous areas. You can find this treasure area in the Windrise, Mondstadt.
It is actually located very close to the first area, which was Falcon Coast. You can find this area to the southeast of Mondstadt, blanketing the coast, near to the Cryo Regisvine boss fight. There is a teleport marker in this area if you have already activated it on your travels.
Use the Seelie and then walk around the area to find all the treasure, netting yourself 60 Iron Coins that you can use in the event shop to buy all manner of items. You can find all the treasure locations marked on the map below, or use the video above if you need help tracking them down in-game. Due to the proximity of the teleporter to the last treasure that we found, you will need to consider the player marker to be a treasure indicator for this area.
The white pickaxe symbols on the above map each denote a treasure location. Remember, you will need to visit Ulman at the Stone Gate in Liyue and speak with him to start the event. He will give you a Treasure Book, and the Treasure Seeking Seelie, and then you will be free to start the event.
Each day, two new areas will appear in the game where you can find the treasure and the Iron Coins, and there will even be special treasure areas as well. The Iron Coins can be used to buy Hero’s Wit, Primogems, Mora, Mystic Enhancement Ore, and a special Seelie from the event shop.