SGNP is the only national park in the world surrounded by tracts of closely-packed human population on all sides.
In fact, it is the only forest reserve in the universe that does not have any buffer space between itself and the city population.
Says Anwar Ahmed, chief conservator, forest and field director, SGNP, "There are only four parks in the world which are 'near' a metropolis. They are in Cape Town, Nairobi, Rio de Janeiro and Mumbai. Unlike the first three, which are adjacent to such parks, SGNP is right in the centre of a very dense metropolis."
He adds, "This park caters to a population of at least 20 million. The density of population just surrounding the park is 29,000 people in a square kilometre. We are blessed to have this forest provide for us."
Spread across 104 sq km, it is one of the two green patches -- the other is the Aarey forest, which is also under attack now -- left in Mumbai's concrete landscape.
It is also one of the most important sources of water for Mumbai and neighbouring Thane; some 8.5 sq km of its area is covered with lakes.
Mamta Vyas, who lives in Highland Park, a society in Mulund, an eastern suburb located right next to the Sanjay Gandhi Park has seen leopards inside her building's premises.
"When we shifted here in 2003, I started hearing that leopards and other wild animals come here. But it was only in 2006 that I first saw a leopard inside our society compound.
"It had jumped over the wall and was hiding inside a gutter/naalah. It created such a pandemonium. Children, people all from the societies gathered around it. Within moments the crowd started pelting stones at the leopard. No one wanted to do anything else. Even the watchman was helpless.
"Thankfully, I knew someone who worked with officials in SGNP. I called him. He came along with Sonu Singh (an IT professional who is also a member of MfSGNP). They did a survey of our building. They held a session in our society and made us realise why leopards are coming here.
"After we have become aware of it, even children know that they are not supposed to throw garbage and other things which will attract stray dogs or rodents. This has now reduced such sightings.
"Even today we see it jump over our walls and walk around. But we are not scared. We know it comes, takes a stroll and goes away.
"We residents don't even point the light of a torch on the animal any more when we see it at night. If we don't disturb the leopards they don't attack us."
Large carnivores are not new to Mumbai.
They have been in this national park for centuries, says Sunetro Ghosal. Once there were tigers too.
In 1829, he says, a tiger was spotted in Malabar Hill, south Mumbai.
Then in the 1860s a tiger was seen swimming across from Mazgaon docks and was shot and killed.