Finding a reliable roblox submarine script is usually the first hurdle for anyone trying to build an underwater adventure game. Let's be real, Roblox physics can be a total nightmare when you're dealing with water. One minute you're cruising along the seabed, and the next, your sub is catapulting into the stratosphere because a collision box touched a terrain voxel the wrong way. It's frustrating, but once you get the hang of how the engine handles buoyancy and linear velocity, everything starts to click.
Why Submarine Physics Are Tricky
If you've ever tried to just slap a "VehicleSeat" onto a metal box and throw it in the ocean, you know it doesn't just work. Unlike cars, which have wheels and a fairly straightforward relationship with gravity, submarines need to exist in a 3D space where they can move up, down, left, right, forward, and backward.
The biggest challenge with a roblox submarine script is balancing the buoyancy. By default, Roblox terrain water applies its own upward force on parts based on their density. If your sub is too light, it'll bob on the surface like a cork. If it's too heavy, it'll sink to the bottom and stay there. Most developers find that the best way to handle this isn't by fighting the density settings, but by using BodyMovers or the newer Constraint objects to manually control the vessel's position and orientation.
The Core Movement Logic
When you're sitting down to write your script, you need to decide how the player is going to control the thing. Usually, you're looking at a LocalScript inside the VehicleSeat that captures input from the keyboard (WASD and maybe Q/E for vertical movement) and sends that data to a server-side script.
You'll probably want to use something like LinearVelocity or VectorForce. In the past, everyone used BodyVelocity, and honestly, a lot of people still do because it's simple. If you go the LinearVelocity route, you can set the relative velocity based on where the submarine is currently facing. This makes sure that when the player presses "W," the sub moves forward relative to its nose, not just forward in the world's coordinate system.
Handling the "Up and Down"
The vertical movement is what makes a submarine a submarine. In your script, you'll need a variable that tracks the target depth. When the player hits the "Rise" key, you increment that value; when they hit "Dive," you decrement it.
A common trick is to use a BodyPosition (or AlignPosition) with the MaxForce on the X and Z axes set to zero. This allows the script to strictly control the Y-axis (the height) while letting other forces handle the forward and side-to-side movement. It prevents the submarine from jittering or slowly sinking when the player isn't touching the controls.
Steering and Rotation
Turning is another beast entirely. Using AngularVelocity is generally the smoothest way to go. You want the sub to have a bit of "weight" to it. If it turns instantly, it feels like a plastic toy. If you add a bit of dampening or a slower ramp-up time in your script, it gives the player the feeling that they're actually piloting a massive hunk of pressurized metal.
Making It Feel Real
A roblox submarine script shouldn't just move the part; it should sell the experience. Think about the small details. When the sub dives, maybe the lighting changes. You can script the Lighting service to adjust the FogEnd or the ColorCorrection based on the submarine's current Y-level.
Also, don't forget the sounds. You can trigger a low hum while the engine is running and maybe a "ping" sound for a sonar effect. All of this can be tied back into the main script. For example, if the Magnitude of the submarine's velocity is greater than 1, you play the propeller sound at a higher pitch.
Dealing with the User Interface
You can't just have a sub floating in the dark without giving the player some info. A decent UI showing the current depth, speed, and maybe a "hull integrity" bar makes a world of difference.
In your script, you'll want to use a RunService.RenderStepped connection to update the UI elements every frame. This ensures the depth gauge doesn't look laggy. You just take the Submarine.PrimaryPart.Position.Y, do a little math to turn it into a positive number (since "down" in Roblox is negative Y), and display it on a ScreenGui.
Common Bugs and How to Squash Them
Every dev who has worked on a submarine game has run into the "spinning death" bug. This usually happens when your BodyGyro or AlignOrientation forces are fighting with the Roblox physics engine's natural inclination to tip things over.
- The Submarine Flips Over: Make sure your
CenterOfMassis low. You can do this by adding a heavy, invisible part at the very bottom of your sub and making it theRootPart. - The Submarine Jitters: This is often caused by the script and the physics engine fighting for control. Try setting
NetworkOwnershipof the submarine's parts to the player who is sitting in the seat. This makes the movement way smoother on their screen. - It Flies Out of Water: If your upward force is too high and the sub hits the surface, it might launch itself. You need to add a check in your script:
if Position.Y > WaterLevel then Force = 0.
Optimizing for Multiplayer
If you're planning on having more than one person in your game, you've got to think about lag. If the server is calculating the physics for ten different submarines at once, things might get choppy.
The best approach is to let the client (the player) handle the movement physics locally and have the server just "verify" that they aren't teleporting across the map. Roblox does a pretty good job of this automatically with VehicleSeats and NetworkOwnership, but it's something to keep an eye on if you notice the subs starting to "teleport" or stutter for other players.
Final Touches
Once you have the basic roblox submarine script running, you can start adding the fun stuff. Maybe a torpedo system? That's just another script that instantiates a part with its own LinearVelocity and a Touched event for explosions. Or how about a robotic arm for picking up treasures?
The cool thing about scripting in Roblox is that once you have the foundation of movement down, you can keep stacking features on top of it. Just remember to keep your code organized. There's nothing worse than coming back to a script a week later and having no idea which variable controls the ballast tanks and which one controls the interior lights.
Building a submarine isn't just about the code, though. It's about the atmosphere. Use your script to dim the lights as the player goes deeper. Make the engine groan when they hit a certain depth. It's those little scripted moments that turn a simple "metal box" into an actual submarine that players will want to explore your world in.
It takes some trial and error, especially with the buoyancy, but keep at it. Most of the "pro" scripts you see in popular games started out as a simple BodyVelocity test in an empty baseplate. Just get the sub moving first, and then worry about making it pretty. Happy coding!