You will get tin ore when you clear tin ore deposits, but you can also get it when you clear obstacles you encounter as you explore the islands, and when you open gifts on Serenilla and Spirits Islands.
You need tin ore to build the Smelter, and to produce tin ingot at the Smelter. It will also prove useful on Dune and Halcyon Islands when you need to upgrade buildings and passages. Tin ore will also come in handy for completing Merchant orders.
To learn more about resources and where to find them, check out our Resources section.