Haa Alif Atoll is the code name based on the letters of the Maldivian alphabet commonly used to refer to the administrative division officially known as Northern Thiladhunmathi Atoll (Maldivian: Thiladhunmathi Uthuruburi) in the Maldives.
It is the northernmost of the 19 administrative divisions (known as "Atolls") of the country, and is the third-largest administrative division in terms of population and land area.
Haa Dhaalu Atoll is the code name based on the letters of the Maldivian alphabet commonly used to refer to the administrative division (known as "Atoll") officially known as South Thiladhunmathi Atoll (Maldivian: Thiladhunmathi Dhekunuburi) in the Maldives.
The administrative division consists of the southern section of natural Thiladhunmathi Atoll (which is shared with North Thiladhunmathi (Haa Alifu) Atoll) and Makunudhoo or Maamakunudhoo Atoll (Malcolm Atoll in the Admiralty Charts) with its large reef.
Thiladhunmathi (also known as Boduthiladhunmathi) is the largest atoll in the Maldives, the Miladhunmadulu group is also naturally a part of Thiladhunmati Atoll, comprising the southern half of the atoll.
Administratively, Thiladhunmathi Atoll together with the Miladhunmadulu group consist of the administrative divisions of Haa Alif Atoll (North Thiladhunmathi), Haa Dhaalu Atoll (South Thiladhunmathi), Shaviyani Atoll (North Miladhunmadulu) and Noonu Atoll (South Miladhunmadulu).
Huvadhu, Suvadive, Suvaidu or Suvadiva is the atoll with the most islands in the world. The atoll is located in the Indian Ocean. It is south of the Suvadiva Channel in the Republic of Maldives with a total area of 3,152 km, of which 38.5 km is dry land. The atoll contains 255 islands.
It is the second largest atoll in the country, after Boduthiladhunmathi (consisting of Haa Alif, Haa Dhaalu, Shaviyani, and Noonu administrative divisions) which has smaller and fewer islands spread across a larger area.