ONE OF THE MOST EXCITING DISCOVERIES BROUGHT ABOUT DURING THE LAST HALF A CENTURY OF SOLAR SYSTEM EXPLORATION IS THAT MARS WAS A HYDROLOGICALLY ACTIVE EARTH-LIKE PLANET. PARTICULARLY SIGNIFICANT IS THE FINDING THAT AN OCEAN PROBABLY OCCUPIED THE MARTIAN NORTHERN PLAINS ~3.4 GA. THIS HYPOTHESIS HAS BEEN THE SUBJECT OF DEBATE AND SCRUTINY FOR NEARLY HALF A CENTURY. PART OF THE CONTROVERSY STEMMED FROM THE OBSERVATION THAT THE PROPOSED PALEO-OCEANIC BASIN LACKS AN APPRECIABLE CONTINUITY OF PALEO-SHORELINE FEATURES. A RECENT INVESTIGATION SUGGESTS THAT THE EMPLACEMENT AND LONG-TERM PRESERVATION OF MEGATSUNAMI DEPOSITS OVER THE PLANET S ANCIENT COASTAL ENVIRONMENTS COVERED THE PALEOSHORELINES HENCE EXPLAINING THEIR ABSENCE (HTTPS://WWW.NATURE.COM/ARTICLES/SREP25106). THIS INVESTIGATION DOCUMENTS TWO POSSIBLE MEGATSUNAMI DEPOSITS A YOUNGER ONE WHICH SHOWS EVIDENCE OF BACKWASH CHANNELS OVER DEBRIS LOBATE FRONTS. AN OLDER ONE LACKING EVIDENCE OF BACKFLOW AND SHOWING DOMINANTLY ICY COMPOSITIONS PERHAPS BECAUSE THE WAVES FROZE DURING THEIR RUN-UP INTO THE HIGHLANDS. THE OLDER AND A YOUNGER MEGATSUNAMI RESPECTIVELY EXTENDED FROM PALEOSHORELINES AT THE -3 800 M AND -4 100 M ELEVATIONS. A FUNDAMENTAL INTERPRETATION IN THE ARTICLE IS THAT MARS EXPERIENCED GLOBAL PALEOCLIMATIC COOLING DURING THE OCEANIC REGRESSION PHASE. THE EVOLUTION OF THE OCEAN S COASTAL ENVIRONMENTS WHICH IS RELEVANT TO THE UNDERSTANDING OF MARS PALEOCLIMATIC EVOLUTION AND POTENTIAL HABITABILITY REMAINS MOSTLY UNKNOWN. HERE WE PROPOSE TO MAP THE DISTRIBUTION OF ALL POTENTIAL TSUNAMI-RELATED LANDFORMS THROUGHOUT THE ENTIRE NORTHERN PLAINS AND THE INTERIOR LOWER FLANKS OF ELYSIUM MONS. WE WILL USE OUR MAPPING TO ESTABLISH SPATIAL AND TEMPORAL RELATIONSHIPS THAT WILL ALLOW US TO INVESTIGATE THE EVOLUTION OF THE NORTHERN OCEAN AND ADD DETAIL TO THE RODRIGUEZ ET AL. (2016) PALEOCLIMATIC RECONSTRUCTION. WAVE HEIGHT AND OTHER HYDRODYNAMIC CHARACTERISTICS WILL BE DETERMINED USING NUMERICAL SIMULATIONS WHICH ALSO GENERATE COASTAL INUNDATION DISTANCES AND BACKWASH PATTERNS. WE WILL COMPARE THESE SIMULATION OUTPUTS TO THE MAPPING RESULTS TO FIND THE BEST MATCHING CASES AND PROVIDE REASONABLE GEOLOGIC RECONSTRUCTIONS OF THE TSUNAMI EVENTS. WE WILL USE OUR MAPPING OF MEGATSUNAMI FEATURES FOR PALEOSHORELINE RECONSTRUCTION WHICH WILL ALLOW US TO INVESTIGATE THE COASTAL PALEOENVIRONMENTS FORMED DURING OCEANIC REGRESSION. THESE RESULTS WILL ALLOW US TO ASSESS THE MARTIAN OCEAN S LONGEVITY AND THE PALEOCLIMATIC CONDITIONS UNDER WHICH IT EXISTED. THESE RESULTS ARE RELEVANT TO CURRENT PALEOCLIMATIC MODELING EFFORTS AND THE SEARCH FOR GEOLOGIC MATERIALS THAT MIGHT RETAIN FORMER LIFE EVIDENCE. TO THIS END WE WILL IDENTIFY ASTROBIOLOGICALLY SIGNIFICANT TSUNAMI DEPOSITS BY COMBINING OUR MAPPING AND NUMERICAL SIMULATIONS TO ESTABLISH THE DISTRIBUTION OF TSUNAMI DEPOSITS THAT ARE MOSTLY COMPOSED OF ERODED OCEAN FLOOR MATERIALS. THIS PROPOSAL ADVANCES THE MDAP OBJECTIVE "TO ENHANCE THE SCIENTIFIC RETURN FROM MISSIONS TO MARS CONDUCTED BY NASA AND OTHER SPACE AGENCIES". THE METHODOLOGY PROPOSED IS DOMINATED BY THE ANALYSIS AND INTERPRETATION OF RELEASED MARS SPACECRAFT DATA SPECIFICALLY FROM THE NASA MARS GLOBAL SURVEYOR MARS ODYSSEY AND MARS RECONNAISSANCE ORBITER MISSIONS AS WELL AS ESA MARS EXPRESS. OUR PROPOSED INVESTIGATION WILL PROVIDE INSIGHTS INTO THE HISTORY OF TSUNAMI-DRIVEN COASTAL RESURFACING IN EARLY MARS OCEANS. OUR ANALYSIS OF SURFACE GEOMORPHOLOGIC FEATURES WITHIN THE PROPOSED TSUNAMI DEPOSITS WILL IMPROVE OUR UNDERSTANDING OF CLIMATE CHANGE IN THE PLANET S EARLY HISTORY AND IDENTIFY AREAS OF ASTROBIOLOGICAL INTEREST FOR FUTURE MARS MISSIONS. THUS IT IS IN DIRECT SUPPORT OF THE GOALS OUTLINED BY MDAP AND THE DECADAL SURVEY PARTICULARLY THOSE RELATING TO GEOLOGICAL PROCESSES THE DISTRIBUTION OF WATER SURFACE-ATMOSPHERE INTERACTIONS HABITABILITY AND CLIMATE.