Tripura
Kalyan Sagar
http://en.wikipedia.org/wiki/Tripura_Sundari_Temple#Kalyan_Sagar
Kalyan sagar is a large lake covering an area of 2.75 acres. The lake is filled with tortoises and fish. The lake is considered sacred by the devotees who come there in large number to feed the fish and tortoises. The lake is set in a area of great scenic beauty surrounded by hills which rise picturesquely in the background.
http://www.indianetzone.com/54/kalyan_sagar.htm
Neermahal
https://www.google.co.in/search?q=neermahal&source
Neermahal meaning 'palace in water' is situated about 55km from Agartala. It is situated in a place of great scenic beauty and there is a palace situated in the middle of the lake which was built by the Maharaja in 1939. The lake is known as Rudra Sagar. It is a royal heritage site. It is a popular tourist site and attracts a large number of visitors.
http://www.tripura.org.in/tours.htm