The Gulf of Riga, Bay of Riga, or Gulf of Livonia (Latvian: Rīgas jūras līcis, Estonian: Liivi laht, Russian: Рижский залив) is a bay of the Baltic Sea between Latvia and Estonia.

The area of the Gulf of Riga is about 18,000 km². The maximum depth is 67 m. The island of Saaremaa (Estonia) partially separates it from the rest of the Baltic Sea. The main exit out of the gulf is the Irbe Strait. Ruhnu island, in the middle of the gulf, also belongs to Estonia.

The Gulf of Riga, as a sub-basin of the Baltic, also includes the Väinameri Sea in the West Estonian archipelago.

Notable cities in this gulf include Riga, Pärnu, Jūrmala and Kuressaare. The main rivers flowing into the gulf are Daugava, Pärnu, Lielupe, Gauja, and Salaca.

The International Hydrographic Organization defines its western limit as "A line running from Lyser Ort (57°34'N), in Latvia, to the S extreme of Œsel Island [Saaremaa], through this island to Pammerort [Pammana Point] (22°34'E), thence to Enmast [Enmaste] Point, the S extreme of Dagö [Hiiumaa, through Dagö to Takhkona [Tahkuna] Point, the N extreme thereof, and on to Spithamn Point [Cape Põõsaspea] in Estonia".

Riga (Latvian: Rīga, pronounced [riːɡa] ( listen)) is the capital and largest city of Latvia. With 657,424 inhabitants ( 2011) Riga is the largest city of the Baltic states, one of the largest cities in Northern Europe and home to more than one third of Latvia's population. The city is an important seaport and a major industrial, commercial, cultural and financial centre of the Baltic Sea region.^{[citation needed]} The city lies on the Gulf of Riga, at the mouth of the river Daugava. Riga's territory covers 307.17 km² (118.60 sq mi) and lies between 1 and 10 metres (3.3 and 33 ft) above sea level, on a flat and sandy plain.

Riga was founded in 1201 and is a former Hanseatic League member. Riga's historical centre is a UNESCO World Heritage Site, noted for its Art Nouveau/Jugendstil architecture and 19th century wooden architecture. The city will be the European Capital of Culture in 2014, along with Umeå in Sweden. The city hosted the 2006 NATO Summit, the Eurovision Song Contest 2003 and the 2006 IIHF Men's World Ice Hockey Championships. It is home to the European Union's office of European Regulators for Electronic Communications (BEREC). Riga is served by Riga International Airport, the largest airport in the Baltic states.