There's over a million people gather for reveillon on Copacabana beach. If you are using public transport you need to buy your metro ticket in advance. There are stages set up along the beach and genuine headline acts attend. Along with carnaval it's probably the biggest party on earth.
The fireworks are incredible, several tonnes worth from barges moored offshore, and it's a dramatic backdrop to start with added to by the collection of cruise liners that gather for the event.
After the fireworks people will party on and of course you have the spectacle of many thousands making tribute to Iemanjá, the goddess of the sea (something we do every year no matter where we are) throwing flowers into the sea and offering prayers in hope of a good new year.
Oh and did I mention you can drink? People bring booze to you and food. So unlike Australia, where public alcohol bans are in place on NYE and revellers only have some shit show, typically from a TV pop contestant, to distract them from the absence of booze.
Reveillon in Salvador is pretty damn good as you have the backdrop of one of the world's most beautiful and largest bays along with some of the world's happiest people but nothing comes close to Rio in terms of spectacle and experience.
So if you ever get the chance and you like fireworks..........