The identification of lobate debris deposits in Arabia Terra, along the proposed paleoshoreline of a former northern ocean, has renewed questions about the existence and stability of ocean-sized body of water in the early geologic history of Mars. The potential occurrence of impact-generated tsunamis in a northern ocean was investigated by comparing the geomorphologic characteristics of the Martian deposits with the predictions of well-validated terrestrial models (scaled to Mars) of tsunami wave height, propagation direction, runup elevation, and distance for three potential sea levels. Our modeling suggests several potential impact craters similar to 30-50km in diameter as the source of the tsunami events. Within the complex topography of flat-floored valleys and plateaus along the dichotomy boundary, the interference of the multiple reflected and refracted waves that are observed in the simulation may explain the origin of the arcuate pattern that characterizes the thumbprint terrain. Plain Language Summary The possibility that a large ocean once occupied the Martian northern plains is one of the most important and controversial hypotheses to have originated from the exploration of Mars. We mapped lobate deposits, which appear and are potential tsunami deposits associated with the existence of a former ocean. We identified the most probable crater sources of the proposed tsunami deposits from a numerical modeling. We tested the ability of the tsunami hypothesis to explain the origin and location of the previously enigmatic thumbprint terrain of northern Arabia Terra which our models suggest were formed by the interaction of the refracted tsunami waves with those reflected by the shore and offshore islands/obstacles. The age of the deposits is determined by the latest crater dating techniques. It provides evidence of the existence of Martian ocean as recently as Early Amazonian (similar to 3 Ga), which has implications for understanding the volatile inventory Mars, its hydrologic and climatic evolution, and the potential for the origin of survival of life.