Cost is one of the fundamental factors that determines where and how a seismic survey will be conducted. Moreover, the cost of 3D seismic acquisition and processing often plays a significant role in determining whether or not a prospect is economic. Unit costs of seismic data acquisition and processing have dropped dramatically as the technology has matured; however, these economies have raised demand for larger and more complex acquisition plans. More than ever, there is a great need to gain efficiency. In this article, I discuss a field experiment carried out to test the feasibility of employing marine sources activated simultaneously. Simultaneous source firing has long been recognized as a possible strategy for achieving dramatic cost reductions in seismic data acquisition. This approach is novel in that it does not require source-signature encoding (although such encoding combined with this approach is beneficial), but, rather, relies on spatial-source positioning to allow for separation of the signals in subsequent data processing. Appropriate data processing sequences separate the interfering signals quite effectively, and this approach may be an attractive economic option for acquiring large 3D surveys, particularly when multiple vessels are already employed as in today's multiazimuth surveys.