Quite frequently we run across deflated helium balloons that have drifted away from land and end up polluting the ocean. Our captains and deck hands are proactive in removing them whenever possible. There are so many problems associated with balloon debris, particularly Mylar balloons. For example, one thing they do is quickly loose their external color and sentimental messages. This makes them semi-transparent. In this conditions they mimic a myriad of clear, gelatinous animals that thrive in the sea. Thus they may easily be confused as food or prey items for predators that regularly feed on gelatinous animals. Although most of the whale and wildlife-watching fleet are similarly tuned in to removing balloon debris, the source of the problem, the widespread use of helium balloons for celebrations and sales promotions, has not yet been stopped.
I took the photograph above a few years ago when we came across part of an auto mall balloon arch and removed it. More photos are on the web at: