This chapter presents a comprehensive summary of previous studies conducted in the Red Sea region, focusing on the Arabian Shield and the Nubian Shield. The Arabian Shield studies included Saudi Arabia and Jordan, while the Nubian Shield included Egypt and Sudan. The chapter also discusses the genesis of the Red Sea and its evolutionary stages, focusing on the Gulf of Aden, Gulf of Aqaba, Gulf of Suez, and Dead Sea. The chapter also summarized the Earth's crust and upper mantle in the Red Sea region, tracing its development from southern to northern regions. Various methodologies have been used, including seismic tomography, receiver functions, gravity measurements, and geodetic analyses, to examine the structures of the northern Red Sea. Results of these previous studies showed variation in crustal thickness across the northern Red Sea region. Shallower Moho depths have been observed in the central Red Sea and Gulf areas, (10–15 km), while was ranging from 30 to 35 km beneath the land. Additionally, the chapter also examines recent seismic activity from 2006 to 2024 along the Red Sea, monitored and analyzed through the Saudi National Network stations (SNSN), Egyptian National Seismic Network (ENSN), and several stations in the Levant region. The analyses revealed that seismic activity in the Red Sea region is primarily concentrated in the central area due to tensile forces from the separation of the African plate from the Arabian plate. The magnitudes of these seismic activities ranged from small to moderate, with depths ranging from shallow to moderate also. A body wave tomographic study was employed to obtain a tomographic image of the northern part of the Red Sea using local and regional seismic data. The results indicated variations in seismic wave velocities, P wave, S wave, and Vp/Vs anomalies beneath the northern Red Sea, Gulf of Aqaba, Gulf of Suez, and the Sinai Peninsula, reflecting the tectonic and complex geological structures present in the region.