The simpliest way to cross over is using the legendary cloak obtained through the Wrathion legendary quest line. Other ways are : * Using a Highwind Albatross to carry you, killing it to land. * Using the [Gleaming Crane Statue], turning and landing near the sanctuary * Purchasing a [Golden Glider], swimming away from the island until you can mount, fly back until you are dismounted and use the glider. Position yourself and land.