I swam the 4.4mi version of the Great Chesapeak Bay Swim! It was a gorgeous day with some great conditions, and the water temp was a balmy 72ºF. I finished in about 2hr4min.
The swim goes between the two spans of the Chesapeake Bay Bridge, so it was really easy to sight and stay on course. The tide switched over the course of the swim, pushing us towards the north span in the beginning and the south span towards the end (visible on the map below).
Sorry again for the screnshot of a map!