Opening up the map in GTA 3 is probably one of your first major goals in getting the most out of the decades-old classic.
The further you go in Claude's revenge tale across Liberty City, the more of the map you can explore.
Initially, only the first island is available - and so by completing certain story missions, more will become available to you. However, if you know the right glitches, you can reach them sooner than you're supposed to.
This page explains how to unlock the closed bridges to help you fully open up GTA 3's map.
On this page:
How to open up the first closed bridge in GTA 3
Initially, Grand Theft Auto 3 will have you restricted within the limits of Portland. This is due to the destruction of the bridge in the southwest that connects Portland and Staunton Island in Liberty City, after it was destroyed by a bomb.
This restriction will be lifted after you complete the 23rd Story Quest named 'Last Requests', after which the tunnel connecting Portland and Staunton Island also will become accessible.
How to open up the second bridge and fully explore the map in GTA 3
Once you reach Staunton Island, you will find yet another restriction, this time rendering you unable to access Shoreside Vale.
The bridge connecting Staunton Island and the south of Shoreside Vale will be permanently raised due to a malfunction, that is until you complete the 41st Story Quest named 'A Drop in the Ocean', after which the bridge will be repaired, the tunnel at the north of Staunton Island will open, and all the subway stations will become accessible for the first time.
How to explore the map in GTA 3 early with bridge jumps and other glitches
If you think that waiting for the game to allow you to get into these two areas is not worth your time, you could also break your way into them, by taking advantage of a few glitches.
These steps from the PS2 originals and still work in re-releases on PC and mobile devices. However, it does not work in the 2021 Definitive Edition - though you can glitch in the tunnel which leads to Staunton Island, it will teleport you back to Portland, meaning you cannot leave the opening island early.
Badinfos on YouTube - embedded above - shows these time-old exploits in motion which might be easier to follow, but the highlights are:
How to access Staunton Island early
To get access to Staunton Island as soon as possible, you can glitch your way there by using a car and driving it into the coastal platform over by the inaccessible tunnel, and getting out of it just as you reverse over the edge, making you appear inside the 'roof' of the tunnel, allowing you take a path to fall through the map and respawn on the Staunton Island side.
It's worth noting that, while you can glitch your way into Staunton Island right at the beginning of the game, it's recommended to wait at least until you finish the first mission since you will be able to do secondary missions in the other islands.
How to access Shoreside Vale early
Once in Staunton Island - either officially or unofficially - you can take things further and also glitch your way into the Shoreside Vale.
You can do this by driving to the southern-most point where the subway station is, taking it down to the railway, driving to the Airport substation on the Shoredale side of the map, and leaping to a passageway so you can fall out of the map.
Again, this will cause you to respawn on the inaccessible side of the map, and it's best to follow the above video for specific locations - but we can assure you it's a straightforward method that allows you to reach the dodo and other late-game points of interest nice and early if you want to play around with it.
Whether you want to explore the map fully officially or unofficially, hopefully the above explains everything you need to know. Happy exploring!