ABSTRACT Exploration of the Mid-Ocean Ridge in recent years has resulted in a better understanding of its complex geologic processes. This new insight was obtained through the use of a comprehensive mapping approach involving three major mapping systems: multi-narrow beam sonar, ANGUS photography, and manned submersibles. These systems were used to span a considerable spectrum of geologic scales ranging from features tens of kilometers in length to ones of a few meters in size. The purpose of this integrated mapping approach was to permit the scientist in the submersible an opportunity to relate his small-scale observations to the larger scale processes of plate tectonics. This mapping approach and its related field techniques are discussed in detail so that both the scientific and technical communities can determine the quality of the data collected and the limits to its interpretation. INTRODUCTION The first major contribution to the mapping of the Mid-Ocean Ridge occurred in 1854 when Maury (1855) published a topographic chart of the North Atlantic Ocean based upon cannonball soundings. That chart revealed for the first time an extensive ridge running down its central axis known then as Telegraph Plateau. In 1912, Sir John Murray published a more detailed chart of the Atlantic as well as the Indian and Pacific Oceans based upon additional wire soundings (Murray and Hjort, 1912). That chart revealed the presence of similar ridges in all three oceans. The next significant contribution came with the German Meteor Expedition from 1925 to 1933 when single acoustic soundings were first made. The resulting chart by Maurer and Stocks (1933) added considerable detail to the Mid-Atlantic Ridge, showing it to be a continuous feature. The final step in the recognition of the Mid-Ocean Ridge for its world-wide dimensions came not from soundings but from seismicity. Work by Rudolph (1887), Tams (1931), Rothe (1954), and finally Gutenberg and Richter (1954) showed that the narrow oceanic belt of shallow seismic events could be correlated to the Mid-Atlantic Ridge. With that insight, Heezen and others (Heezen et al., 1959; Heezen, 1960) used their extensive inventory of echo-sounding profiles to propose the existence of a global mountain range 70,000 kilometers in length, making it the largest geologic feature on the surface of the earth. From 1960 to 1980, a tremendous amount of new information was obtained about this feature and its relationship to the evolving concepts of global tectonics. Paralleling this scientific exploration has been a continuous development in deep-water mapping techniques. The most intensive utilization of these new techniques occurred as a part of Project FAMOUS in the early 1970's. This science program sought to relate small-scale observations made from manned submersibles to the large-scale problems of plate tectonics. As a result, a series of investigative tools were employed to obtain a continuous spectrum of measurements which could span this great range of scales. At the upper end of the spectrum was a need for a regional reconnaissance of the Ridge"s tectonic fabric.