Geographically, Egypt is the North African country nearest to Israel. However, "closest" is relative: the straight-line distance across the Mediterranean Sea is approximately 250 kilometers (155 miles) from Israel's southern coast (near Rafah/Eilat) to Egypt's Sinai Peninsula.
Despite the distance, Egypt-Israel relations are pivotal: peace treaty, security coordination in Sinai, natural gas cooperation, and the Rafah crossing for Gaza. The "closeness" is political and strategic, not just geographic.
So while Egypt is the answer, don't plan a day trip by boat—the Mediterranean crossing involves border controls, not a ferry ride.