>>Use CWCheat with any kind of custom firmware.

Returning to Portland Island from Staunton Island or Shoreside Vale: Take a Predator or Speeder (found near The Condos at Newport) and drive it to Portland Beach. Beach the craft, run to your Portland Island Safehouse to save, and then return to the beach. The boat should still be there to take you back to Staunton Island.

Returning to Portland Island from Shoreside Vale: Take the Predator at the South Runway of Francis International Airport and beach it at the pier at Bedford Point. Then, take another boat from the piers at The Condos in Newport back to Portland Island.

Getting to Shoreside Vale from Staunton Island (The Speeder Jump): This is the only method to reach Shoreside Vale while it is locked. Barriers prevent using boats. Get a Speeder (usually at the south dock at The Condos in Newport) and head towards the Rockford Ferry Terminal. Approach the ferry ramp, but aim for the rocky shoreline to its left, which is angled like a ramp. Hit this area at high speed to launch into the air and land in the ferry terminal parking lot. Next, take the Landstalker parked nearby and push the Speeder towards the other ferry ramp on the other side of the northern barrier. Once the Speeder is on the edge of the ramp, exit the Landstalker and push the boat into the water by hand. Get in and travel to Shoreside Vale. Alternatively, if you hit the ramp just right (on the right side near the corner, with calm water), you can bounce the Speeder over the road railings and into the water on the other side without needing to push it.

Activating the Shoreside Lift Bridge Early (The See The Sight Before Your Flight Trick): This exploit will make the Shoreside Lift Bridge operational early. Go to Shoreside Vale and activate the "See The Sight Before Your Flight" side-mission. The first sight is Cochrane Dam. The second sight is on Staunton Island. When you activate the second sight, the lift bridge will be lowered for you to complete the objective. After this, the lift bridge will be operational, making travel between Staunton Island and Shoreside Vale easier for early exploration. This trick does not work with the Callahan Bridge.

Achieving a 6-Star Wanted Rating Early (The AWOL Angel Wanted Rating Trick): In the early game, the maximum Wanted Rating is 4-Stars. By sneaking to Shoreside Vale early, you can reach 6-Stars by doing the "AWOL Angel" side-mission in Wichita Gardens. This is useful for acquiring a Rhino (tank) for Vigilante Missions or causing havoc. Before going to Shoreside Vale, collect all Hidden Packages on Portland Island to get Pistol and Shotgun Weapon Icons, and pick up sub-machine gun ammo. Once in Shoreside Vale, find Police Bribes and head near The Complex in Wichita Gardens. Start killing pedestrians until you reach a 4-Star Wanted Rating, then get on the parked Angel to start the "AWOL Angel" side-mission. Do not shoot your intended target; instead, shoot everything else. You may reach a 5-Star Wanted Rating before time runs out and you fail the mission. Upon failing, you will retain your Wanted Rating and be back near the bike. Repeat the side-mission until you achieve a 6-Star Wanted Rating. Then, try to get the Rhino without being killed or caught. Use Police Bribes to lower your Wanted Rating before starting Vigilante Missions. You can also reach a 6-Star Wanted Rating during Vigilante Missions.