The gondola stops on the way, so you're going to have to find another way to get to the beach with survivors. Start by shooting a rope arrow at the interactive spot. Slide down the rope.
Locate a ladder and make your way up until you reach the higher level of the metal structure. Slide down another zip-line. When the ride is over, get ready for another battle.
I suggest keeping to a cover during the whole firefight, moving left or right only when you need to. Initially, use the submachine gun (or the assault rifle) and make use of the explosive barrels.
When you run out of ammo, look around for supplies or switch to a pistol or the bow. Don't waste your supplies on the enemies sliding down the zip-line; it's better to take them down hand-to-hand (climbing axe) or at close distance (shotgun). Keep fighting until a cut-scene is triggered.
Now it's time for a long action sequence cut into several parts. When you regain partial control over Lara, make your way up using "uncovered" pieces of the ship as you go.
Go up, then right, jumping when needed. Go up again. Once you reach a safe platform, start running straight ahead, but make sure to go round the chasm.
Soon, Lara will start sliding down a zip-line, but it won't be a ride free of excitement. As soon as the game slows down, press the action button to let go of the line and grab onto the one below.
Repeat the same with the second zip-line. Be ready to press the action button when the time is right so that Lara doesn't die in the collision with the metal structure.
Use the shotgun to blast through the barricade. Wait until Lara grabs onto the line. Let go of it and grab onto the one below.
Press the dodge button as soon as Lara finds herself just above the water. Lastly, blast through another barricade.
Get out of the water and take the only available path, squeezing through some rocks on the way. It shouldn't take long before you reach Shipwreck Beach.
There's nothing stopping you from exploring the beach now; there's a multitude of collectibles to find. Personally, though, I recommend putting it off for later because the lack of equipment will hinder you from reaching all places. To advance the plot, head south-west towards the boat the survivors are working on (reward: 400 XP).