Maṭṭakkaḷappu (மட்டக்களப்பு English: Batticaloa ) is a major city in the Eastern Province, Sri Lanka, and its former capital. Batticaloa is situated 314 Km (195 Miles) from Colombo on the east coast. Its average elevation is around 7 meters. It occupies the central Part of Eastern Sri Lanka and covers a land area of approximately 2633.1 Square Km. The District accounts for 3.8% of the Countries Total Land area. It stands on a long, sandy spit of land pointing northward and separated from the mainland by a large brackish lagoon which extends southward for many kilometres. There are several islands within the Batticaloa Lagoon such as Puliayantheevu, Buffaloa Island and Bone Island. Many bridges are built across the lagoon connecting the landmasses and the islands. The Puliayantheevu is the metropolitan place of the city.
The original name of the region being the Tamil "Matakkalappu" (Muddy Swamp). According to Mattakallappu Manmiyam (மட்டக்களப்பு மான்மியம், English: The Glory of Batticaloa - A Tamil historical book which contains facts of the history of Batticaloa; compiled from the collections of palm-leaf manuscripts, copper plate inscriptions & inscriptions.) the word Mattakkallpu consists Tamil words "Mattu" (மட்டு) Matta-derived from "Mattam" (மட்டம்) means 'flat' and geographical name KaLappu. Mukkuwa named this place as KaLappu-Mattam or boundary of lagoon later it became Matta-Kallappu or Flat Lagoon. Batticaloa is a Portuguese derivation. Batticaloa means the "Kingdom of Rice" in Potuguese. Also, Batticaloa has a nickname, "Land of the singing fish" (Tamil: மீன் பாடும் தேன் நாடு) due to musical sounds that related to fish or aquatic creature in the Batticaloa Lagoon near the Kallady Bridge. BBC Radio 4 able to recorded the mysterious sound in Batticaloa Lagoon. The sound was broadcast by Sri Lanka Broadcasting Corporation in 1960s with the help of Rev. Fr. Lang, a Catholic priest.