The Red Sea (Arabic: البحر الأحمر - بحر القلزم, romanized: Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; Hebrew: יַם-סוּף, romanized: yam sūf or Hebrew: הַיָּם הָאָדְוֹם, romanized: hayyām hāʾāḏōm; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ Phiom Enhah or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ Phiom ǹšari; Tigrinya: ቀይሕ ባሕሪ Qeyih Bahri; Somali: Badda Cas 𐒁𐒖𐒆𐒆𐒖 𐒋𐒖𐒈) is a seawater inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab el Mandeb strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez (leading to the Suez Canal). It is underlain by the Red Sea Rift, which is part of the Great Rift Valley.

The Red Sea has a surface area of roughly 438,000 km² (169,000 sq mi), is about 2,250 km (1,400 mi) long, and — at its widest point — 355 km (221 mi) wide. It has an average depth of 490 m (1,610 ft), and in the central Suakin Trough it reaches its maximum depth of 3,040 m (9,970 ft).

The Red Sea also has extensive shallow shelves, noted for their marine life and corals. The sea is the habitat of over 1,000 invertebrate species and 200 types of soft and hard coral. It is the world's northernmost tropical sea, and has been designated a Global 200 ecoregion.