This tour comes not only as a fad for the western tourist, happily it is also putting some money in the pockets of Mumbai's slum dwellers and in the process highlighting their plight.
From a tiny office perched above a photocopying shop in Colaba, the suburban metropolis of this jam-packed city, a young Briton, Chris Way is offering an uncommon tour.
The 31-year-old from Stourport, in Worcestershire, sends small groups of tourists on walking tours of the slums.
Mr Way has started his tours at a time when there is a sudden Western fascination with Mumbai's slums, fuelled by the bestselling novel Shantaram by Gregory David Roberts - soon to be turned into a Hollywood movie starring Johnny Depp - in which an Australian bank robber who has escaped from prison hides out in them.
There is little privacy in the slums, and every open doorway lets onto a family's entire home. So Mr Way is careful to stress that his tours are not designed to invade the slum-dwellers' privacy. Tourists are asked not to take photographs except in particular areas where the locals have agreed, and not to hang about in some places but to walk straight through.
The walking tours takes through some extraordinary scenes: winding streets like subterranean tunnels where the houses on either side touch overhead and the light never enters; warehouses piled to their wooden rafters with tens of thousands of empty metal cans and other items.
One of the most startling discoveries on Way's tours, is 'Dharavi,' a place with a reputation for grinding poverty, is actually home to a thriving economy, with an annual turnover of £350m. There are even textile businesses that export cloth to the US. There are Americans who have no idea the cloth for their T-shirt was dyed in a fetid slum in India.
Mr Way's Indian business partner Krishna Pujari says "This is a place of thriving legitimate business. "This is what we want to show, that the common perception in India, that Dharavi is just a place of criminals, is wrong."
Indeed many of the residents in the slums are hard-working and decent people while the environment of the slums could also pose threats from criminal elements.
Mr. Way who makes most of his money from coventional tours says, "the slum tours are about more than making money from a tourist attraction. For one thing, 80 per cent of the profits go to a charity that helps slum-dwellers. We want to help change perceptions, both in India and internationally."
Mumbai the commercial capital of India is also a city of slums. It's not possible to spend more than an hour or two in the city without seeing one from the outside. Even in the wealthiest neighbourhoods, across the street from plush apartment blocks you will find a slum.