Doc's ProPlugs - Preformed Protective Vented Earplugs
The Docs earplugs look more like a hearing aid than an earplug, but that is part of the reason that they are so great. Their unique design helps to prevent all kinds of medical conditions because of their full ear coverage. They come in an array of sizes which allows for a more personal fit but may also make it difficult to find the right fit at first. They are very reasonably priced and quite comfortable when you find the right fit. They are meant for scuba diving but work great for swimmers too as long as you have a swim cap to help keep them in place.