If there is any NE to SE wind and swell, I much prefer returning to STT via Culebra instead of via Vieques. The shallow east end of Vieques gets very rough with the seas piling up for a couple miles offshore until you get into deeper water. From Culebra/Culebrita, it tends to settle down more quickly into organized rollers and when you get to Sail Rock, halfway to STT, you can feel the seas start to ease.