Lake Almajas (also known as Alma) lies in the Ignalina district of northeastern Lithuania, about 11 km northwest of the town of Ignalina, within Aukštaitija National Park — the country's oldest national park, established in 1974 and home to over a hundred interconnected lakes.

The lake covers around 106 hectares, stretching 2 km from north to south and reaching up to 1 km in width. It was formed in a hollow left by a melting block of glacial ice, and reaches a maximum depth of 10.5 metres. Its northern and southeastern shores are low, while the remaining banks rise steeply from the water. The small Pliaušė stream feeds the lake from the north, and the Almaja river flows out at the southeastern end, carrying its waters toward the Žeimena river basin.

Surrounded by the hilly, forested landscape typical of the Aukštaitija highlands, Almajas is a popular spot for kayaking and angling, and forms part of the water trail network connecting the park's lake chains.