The United Arab Emirates occupies 83,600 square kilometers on the southeastern Arabian Peninsula, bordered by Saudi Arabia to the south and west and Oman to the east. The country extends 700 kilometers along two coastlines: 650 kilometers on the Persian Gulf and 90 kilometers on the Gulf of Oman, creating the only nation in the Arabian Peninsula with dual maritime access. The northern emirates face the shallow waters of the Persian Gulf where depths rarely exceed 35 meters within 20 kilometers of shore, while Fujairah on the eastern coast confronts the deeper Gulf of Oman where the continental shelf drops rapidly to depths exceeding 3,000 meters. The Strait of Hormuz, located 220 kilometers northeast of Abu Dhabi, channels all Persian Gulf maritime traffic through a passage 54 kilometers wide at its narrowest point between Omani territory and Iran. The Musandam Peninsula, an Omani exclave separated from the rest of Oman by UAE territory, forms the southern boundary of this strait.
The Hajar Mountains enter the UAE from Oman, running parallel to the eastern coast through Ras Al Khaimah and Fujairah. Jebel Jais, the highest peak in the UAE at 1,934 meters above sea level, lies in Ras Al Khaimah approximately 25 kilometers from the coast. These mountains formed between 70 and 40 million years ago when oceanic crust thrust over continental margin during the collision of the Arabian and Eurasian plates, creating ophiolite sequences where ocean floor rocks now sit exposed at elevation. The mountains receive 120 to 350 millimeters of annual rainfall depending on elevation and orientation, approximately three to seven times the precipitation of coastal areas. Jebel Hafeet, a separate limestone massif rising to 1,249 meters near Al Ain, stands isolated from the main Hajar range, its Cretaceous carbonate formations dating to 66 to 145 million years ago containing marine fossils that document when this region lay beneath the Tethys Ocean.
The Rub' al Khali desert, known as the Empty Quarter, extends into the southern UAE from Saudi Arabia, covering approximately one-third of the country's landmass. This is the planet's largest continuous sand desert, spanning 650,000 square kilometers across four nations. Within UAE territory, dunes reach heights of 80 to 100 meters in the Liwa region, their crests running roughly east-west shaped by prevailing shamal winds from the northwest. The sand consists primarily of quartz grains weathered from ancient river systems that flowed when Arabia experienced wetter climates during interglacial periods, the most recent ending approximately 6,000 years ago. Between dunes, sabkha flats contain evaporite deposits where shallow groundwater rises by capillary action and evaporates, leaving crusts of gypsum and halite. These salt flats occupy an estimated 7,000 square kilometers of UAE territory, expanding inland from coastal areas where marine transgressions during the Holocene deposited marine sediments subsequently exposed by falling sea levels.
The coastal zone exhibits three distinct environments: rocky headlands in the north and east where Hajar Mountain geology meets the sea, extensive sabkha plains along the Abu Dhabi coast, and sandy beaches interspersed throughout. Abu Dhabi emirate contains approximately 200 islands, most uninhabited, formed as rising Holocene seas flooded a gently sloping coastal plain. Sir Bani Yas Island, located 250 kilometers southwest of Abu Dhabi city, covers 87 square kilometers, making it the largest natural island in the UAE. The island rises to 135 meters at its highest point, composed of salt dome structures that pushed upward through surrounding sediments. Mangrove forests occupy 110 square kilometers of UAE coastline, concentrated along Abu Dhabi's protected bays where salinity ranges from 40 to 75 parts per thousand, well above normal seawater at 35 parts per thousand. These mangroves consist entirely of Avicennia marina, the only species capable of tolerating such hypersaline conditions, extracting freshwater through root membranes that exclude up to 90 percent of salt.
Dubai and Abu Dhabi have constructed extensive artificial coastlines since 2000. Palm Jumeirah, completed in 2006, added 78 kilometers of coastline to Dubai using 94 million cubic meters of sand dredged from offshore deposits and 7 million tons of rock for breakwaters. The World Islands, constructed between 2003 and 2008, comprise 300 artificial islands arranged to approximate a world map when viewed from above, though many remain undeveloped. These projects required removing sand from depths of 10 to 30 meters offshore, altering seafloor bathymetry and modifying local current patterns that historically moved sediment parallel to shore. Environmental monitoring conducted by Dubai Municipality from 2005 to 2008 documented turbidity increases during construction exceeding 200 milligrams per liter compared to background levels below 10 milligrams per liter, though measurements returned to near-baseline within 18 months of construction completion.
The UAE climate classifies as hot desert under the Köppen system, designation BWh, characterized by high temperatures and minimal precipitation. Coastal areas record mean July maximum temperatures of 40 to 42 degrees Celsius with humidity frequently exceeding 90 percent, while inland desert regions reach 45 to 48 degrees Celsius with humidity below 20 percent. January mean temperatures range from 18 to 20 degrees Celsius on the coast to 12 to 15 degrees Celsius in mountain areas. Annual rainfall averages 78 millimeters in Abu Dhabi and 94 millimeters in Dubai based on records from 1960 to 2020 maintained by the National Center of Meteorology. Rainfall concentrates between December and March, delivered primarily by shamal weather systems that draw moisture from the Mediterranean and Red Sea. Individual events rarely exceed 20 millimeters, but exceptional storms have produced 100 to 150 millimeters in 24 hours, most recently in March 2016 when Dubai recorded 144 millimeters at Dubai International Airport, approximately 150 percent of typical annual totality.
Summer shamal winds blow from the northwest at sustained speeds of 30 to 45 kilometers per hour, with gusts reaching 60 to 80 kilometers per hour during intense events. These winds lift fine particles into the atmosphere, reducing horizontal visibility to 1,000 meters or less during dust storms that occur 10 to 20 days annually based on visibility records from 1985 to 2020. Winter brings occasional fog when radiative cooling creates temperature inversions, trapping moisture in surface layers. Fog occurs most frequently from December through February, averaging 30 to 40 days annually in coastal areas and up to 50 days in inland desert regions where temperature inversions persist longer after sunrise. Dubai International Airport logged 1,168 fog events between 2000 and 2020, with 70 percent occurring between 0400 and 0900 local time when surface temperatures reach their diurnal minimum.
Wadis form the UAE's primary drainage system, channels that flow only after rainfall events. Wadi Wurayah in Fujairah drains 34 square kilometers of mountain terrain, descending 800 meters over 12 kilometers before reaching the coast. Flow events last hours to days depending on rainfall intensity and duration, with discharge rates ranging from 0.5 to 15 cubic meters per second based on measurements collected by the Ministry of Climate Change and Environment between 2010 and 2020. Permanent pools persist in upper reaches where bedrock geology creates natural basins, maintaining populations of Arabian toad (Duttaphrynus arabicus) and fish species including Garra barreimiae found nowhere else globally. Wadi Bih, draining portions of Ras Al Khaimah, extends 40 kilometers from the Hajar Mountains toward the coast, though most flow infiltrates alluvial deposits before reaching the sea, recharging groundwater aquifers that have supported human settlement since at least 3000 BCE based on archaeological evidence from Shimal and Julfar sites.