Alpes-Maritimes (French: [alp(ə)maʁitim]; Occitan: Aups Maritims; Italian: Alpi Marittime; lit. 'Maritime Alps') is a department of France located in the country's southeast corner, on the Italian border and Mediterranean coast. Part of the Provence-Alpes-Côte d'Azur region, it encompasses the French Riviera alongside neighbouring Var. Alpes-Maritimes had a population of 1,094,283 in 2019. Its prefecture (and largest city) is Nice, with Grasse as the sole subprefecture.

Alpes-Maritimes has become one of the world's most attractive tourist destinations in recent decades, featuring renowned cities and towns such as Nice, Grasse, Cannes, Antibes, Menton, Èze, Roquebrune-Cap-Martin and Sainte-Agnès, as well as numerous alpine ski resorts. It also entirely surrounds the Principality of Monaco. The department's inhabitants are called Maralpins (masculine) or Maralpines (feminine) but are more commonly referred to as "Azuréens"; its flag and arms are those of the City of Nice. In terms of politics, Alpes-Maritimes is one of France's most right-wing departments, as the majority led by The Republicans in the departmental council holds all but two of the 54 seats following the 2021 election.

The Alpes-Maritimes department is surrounded by the departments of Var in the southwest, Alpes-de-Haute-Provence in the northwest; Italy to the north and east; and the Mediterranean Sea to the south. It surrounds the Principality of Monaco on the west, north and east.

Its topography is very mixed. As its name suggests, most of the department is a constituent part of the overall topographic Alps – including the Maritime Alps – but it also has the distinction of being a coastal district with its Mediterranean coast. The coastal area, urbanized and densely populated (shaded in red on the map), includes all the cities in an almost continuous conurbation from Cannes to Menton, while the larger but sparsely populated mountainous area (light green) is fully rural with the exception of the three large resorts of Valberg (created in 1936), Auron (created in 1937) and Isola 2000 (created in 1971).

The highest point of the department is the Cime du Gélas (3,143 metres, 10,312 ft) on the Franco-Italian border which dominates the Vallée des Merveilles further east. The summit of Monte Argentera is higher at 3,297 metres (10,817 ft) above sea level, but it is located in Italy. There is also Mount Mounier (2,817 metres, 9,242 ft), which dominates the south of the vast Dôme de Barrot, formed of a mass more than 900 metres (3,000 ft) thick of red mudstones deeply indented by the gorges of Daluis and Cians. Except in winter, four passes allow passage to the north of the Mercantour-Argentera massif whose imposing 62-kilometre-long (39 mi) barrier is covered in winter snow which is visible from the coast. From the west, the Route des Grandes Alpes enters the Cayolle Pass (2,326 metres, 7,631 ft) first on the way to the Alps and the sources of the Var in the commune of Entraunes. Then the route follows the Col de la Bonette – the highest pass in Europe at 2,715 metres (8,907 ft) – to connect to the valley of the Tinée then the Ubaye. Further east, the Col de la Lombarde (2,350 metres, 7,710 ft) above Isola 2000 allows access to the shrine of Saint-Anne de Vinadio in Italy. Finally, at its eastern end, the Col de Tende (1,871 metres, 6,138 ft) links with Cuneo in Italy.

The only region of the Alps close to Nice has an afforestation rate of 60.9%, slightly higher than the average of the department and well above the average of 39.4% for the Provence-Alpes-Côte d'Azur region.

The rivers in alphabetical order are:

It is the climate that made the Côte d'Azur famous. The current department of Alpes-Maritimes, however, does not have only one climate, the complex terrain and high mountains divide the department between those who are well exposed (the south-facing side) and those which are less (the north-facing side) and even with the mild Mediterranean climate there can be violent storms and prolonged droughts.