Fjallavatn

{{Short description|Lake in the Faroe Islands}}{{Infobox lake

| name = Fjallavatn

| image = Faroe_stamp_513_vagar_-_fjallavatn.jpg

| caption = Stamp FO 513 of Postverk Føroya
Issued: 7 February 2005
Artist: Eli Smith

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| location = Vágar

| coords = {{coord|62|07|21|N|7|17|57|W|region:FO_type:waterbody_source:dewiki|display=inline,title}}

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| basin_countries = Faroe Islands

|pushpin_map=Faroe Islands

| length =

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| area = {{convert|1.02|km2|abbr=on}}

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Fjallavatn is the second largest lake in the Faroe Islands.{{Cite web|url=https://www.visitfaroeislands.com/place/fjallavatn/|title=Fjallavatn - Visit Faroe Islands|access-date=2020-03-31}} It is situated on the island of Vágar and its size is 1 km².