You will appear on a small island, and there will be a huge ocean nearby. Geodes are scattered across the ocean, but it will not be difficult to find them, since many of them are located close to each other!
Amethyst geodes are the only source for obtaining amethyst fragments. If you want to increase their number using this seed, then use the guide to create Automatic farm for Minecraft 1.17.
In the ocean, you can also find several sunken ships with useful loot.