Underwater Base MOC: Build a Transparent Dome Deep-Sea Station
Here is the short version: this underwater base MOC needs about 4,200 parts, covers roughly 70×60 cm once finished, takes around 15 hours at two hours a day, and costs about 850 RMB in parts. The design is built around a transparent dome main chamber, backed up by three connecting tunnels, a deep-sea derrick and two submersibles. Blue transparent elements make up around 30% of the total part count, and they do a convincing job of faking underwater light. The instructions come from the brickplan platform, and the parts list is broken down module by module, so this is a build for intermediate builders and up.
Step 1: Main Chamber Base and the Transparent Dome
Start with a 48x32 stud baseplate to lay out the base foundation, then build an 18-stud-diameter circular main chamber in the central area. The dome goes up layer by layer with transparent curved elements, each ring pulling in tighter until you have a hemisphere. Leave a 3x3 stud circular hatch at the top so a lid can be added. Inside, fit out the chamber with a console, seats and plants so the interior detail reads clearly through the transparent pieces. This step uses about 1,400 parts.
Step 2: Three Connecting Tunnels
The three tunnels run to a lab on the left, a habitat on the right and the deep-sea derrick at the front. Each one is 14 to 18 cm long and 8 studs in diameter, built from transparent half-cylinder pieces. Round flange elements join both ends of each tunnel to the airlock doors, and an LED strip runs out from inside the chamber, so once it is lit the whole tunnel reads as an underwater corridor. The three tunnels use about 900 parts.
Step 3: Deep-Sea Derrick and Submersibles
The deep-sea derrick is a four-legged steel frame about 22 cm tall, with a rotating crane arm on top and a seabed sampling cage hanging beneath it. Two submersibles park on either side of the derrick, with yellow bodies and transparent cockpits, and a tail propeller that turns by hand. Dark grey and orange parts dress the base of the derrick as hydraulic lines. This module uses about 1,000 parts.
Step 4: Finishing Touches and Lighting
Finish by adding seabed rock, coral and kelp decorative elements, scattered around the base so the scene looks natural rather than staged. Adding a set of cool white light bricks is recommended: one on top of the main chamber and two at the tunnel entrances. Once powered, the blue-white light glows out through the transparent elements and the underwater mood arrives all at once. When everything is complete, check your parts against the module-by-module list on the brickplan instruction page.
FAQ
Q: Where do I download the underwater base MOC instructions?
A: Search for "underwater base" on the brickplan site to find this plan. It includes high-resolution step-by-step views and a parts list split by chamber, and the PDF is free to download after registering. It also works zoomed in on a phone.
Q: Is the transparent dome hard to build?
A: Not especially. The key is to follow the layer-by-layer closing order in the instructions, using the fixed number of curved elements per layer and locking each ring to the one below with clips. The plan states the curved element count for every layer clearly, so it will not lean if you follow it.
Q: How long does the whole build take?
A: At two to three hours a day, about 15 hours. The main chamber and dome take the most time at roughly 6 hours, the tunnels and derrick take two to three hours each, and the remaining time goes into decoration and lighting.
Q: What does it cost to buy all the parts?
A: About 850 RMB. Transparent curved elements and transparent half-cylinder pieces are the big-ticket items at around 350 RMB. The brickplan page has a parts list, so you can tally what you already own first and only order the gaps, which saves a fair amount.
Q: How are the light bricks wired?
A: The light bricks run on USB power. Route the cable along the recessed channel reserved in the floor of the tunnels, and leave a feed hole at the hatch. Fit the lights before sealing the dome roof to avoid having to redo it later. A set of three lights costs about 60 RMB.