It depends on what your idea of "major" is. The most beautiful
(i.e attracts the most tourists)? or the most useful in terms of
energy resources etc. Lake Sumatra and Kalimantan are definitely
major though.
Lake Toba, North Sumatra; Lake Batur, Bali; Lake Segara Anak,
Mount Rinjani, Lombok; Lake Maninjau, West Sumatra are some. See
the link below.