Brown Lake is a lake on North Stradbroke Island, in Queensland, Australia. There are no native fish in the lake.
Known as a perched lake like other lakes on the sandy islands in the regions of South-East Queensland and Wide Bay-Burnett, it retains its water due to a layer of leaves lining the lake floor. This is particularly apparent in the Brown Lake as tannin is exuded from the leaves, dropped from surrounding Paperbark Melaleuca and Tea-trees Leptospermum, stains the water to a rich brown colour not dissimilar to that of tea.
Because of the high levels of organic material in the lake's waters it is considered to be warm monomictic.