Shops are places where you can sell almost anything, they can be found mostly on the second and third sea. All these shops are all controled by "The shop keeper", other than just a shop, they can also serve as a temporary safe zone.
Location:
First sea:
In middle town, in one of the stall near the fountains.
Second sea:
Inside the cafe, in the basement, there will be a shop opposite of the ladder going down with a sign reading "SHOP".
In green zone, there will be a small tent near the quest giver.
Third sea:
In port town, near spawn, there will be a small hut, under the "Set spawn" NPC with a sign reading "SHOP"
On the sea, while traveling on boat, a floating shop can be seen drifting around the sea (it's about the size of swan/flower ship). While getting close to the floating shop, you cannot get attack by sea beast or ship raids.
In the mansion, in one of the side, a door is open, walk inside and you'll see the shop.
Shops: (SELLING PRICES WILL NOT BE AFFECTED BY x2 MONEY)
Shops are places where you can sell and buy things you need. You can sell unwanted materials and fruits (including from your inventory) here. Depending on the stock, if a fruit isn't on it, selling prices will go up (+2% every time it doesn't show up), but if it's currently on, the price of that fruit will drop by 30% of its original price, if it isn't, it'll sell for an extra 5%. Fruit prices also depends on which sea you're in, in first sea, people are more likely new, so prices will be higher than other sea by 10% and in third sea, people will have more legendary fruits, prices of those will go up by 10%.
However, prices of fruits will drop by 10% the more you sell the same fruit, this is to prevent people with +1 fruit to exploit inf cash, for example: dough hasn't been in stock once so you sell dough for 2.940.000$, if you sell it another dough, it'll sell for 2.646.000$.
You can also buy fruit, If someone before you sell a fruit, that fruit will be kept by "The shop keeper" and the price depends on the stock (same as above, except it's reverse)
Another thing the shop sell is material. The price of materials depends on its rarity, the rarer something is, the more expensive it is. For common and uncommon materials, you can buy it in bulk and infinitely, but there is a limited amount of rare material. You can also sell unwanted materials for its rarity:
Common: 1.000$ each.
Uncommon: 5.000$ each.
Rare: 25.000$ each.
Legendary: 50.000$ each.
Mythical: 110.000$ each.