Final Fantasy XIV players have all sorts of new content to explore with the release of Patch 6.5, including additions to the Island Sanctuary. With a new area comes new materials to harvest, and new crafts to make with those materials. Hawk's Eye Sand is one of these.
To get some, you'll need to head to the Island Sanctuary's new cave area, the Mother Lode (X: 23.5, Y: 21.5). Hawk's Eye Sand can be gathered from the Island Crystal Cluster nodes, and no tools are necessary. Regardless of what tools you have in your inventory, you'll always get the sand from these crystals.
Hawk's Eye Sand is needed to craft both of the new Island Sanctuary tools: the Islekeep's Mythril Pickaxe and the Islekeep's Chisel. In order to make these, you'll need three sand each. There are four crystals in the cave that are available to gather from, so you may want to clear out the room of its resources to get the nodes to respawn for you. Once you've gathered six of the Hawk's Eye Sand, you'll have enough to update your tools.
After getting those two new tools, you'll have access to three more materials. The Island Mythril Pickaxe will unlock the Island Durium Sand and Island Gold Ore, while the Island Chisel will unlock Island Crystal Formations. It can be confusing to figure out just how to get the materials you need to move forward on your island, but progressing is fairly linear once you know where to look.