Giant's Tank (Tamil: கட்டுக்கரை குளம், romanized: Kaṭṭukkarai Kuḷam; Sinhala: යෝධ වැව Yōdha Væva) is an irrigation tank in northern Sri Lanka, approximately 10 mi (16 km) south east of Mannar.

[1][2] On the other hand, Mudaliyar C. Rajanayagam in his book Ancient Jaffna suggests that the tank was probably constructed by the Nagas.

[4] Rajanayagam has suggested that the Megisba lake mentioned by Pliny in Description of Taprobane was in fact Giant's Tank.

[5] Consideration was given to renovating the tank during Dutch Governor Willem Jacob van de Graaf's administration in the eighteenth century but nothing happened.

[7][8] The waters were then diverted to Giant's Tank by a 12 mi (19 km) inlet channel (alawakkai).