Rob and I worry every time we take Caitlin to an off-leash beach. Once the leash is gone, we might as well not exist. She races off in the direction of the nearest excitement and never again so much as glances in our direction.
She quite obviously has a wonderful time.
Our only cause for hope of ever getting her back is that she almost always chooses one particular dog to be her "sheep." She stays within a few feet of that dog wherever he goes, never taking her eyes off him. She becomes so focused that nothing else in the world apparently exists for her--including me sneaking up behind her to put her on the leash.