50,000 coins available as soon as you start the game. (rob the gnomes of their gold its legal).
1. Find the sewers
Go down here
2. Go to this place
Go here and look down onto the pipe
3. Jump down onto the pipe
Jump i said 
4. Walk along the pipe then kick your way into the pipe ahead of you
After jumping down onto the pipe walk along it and use the kick ability to boost your way into the pipe in front of you
5. Walk
this is pretty self explanatory
6. Money
Open the chests (or not idc)
note: I tried to make this guide as ape brain friendly as i could.