The exterior model for Optimum's secret lab was the Deep Base Bio Lab.
The Offshore Base Atmosphere Observatory includes Doppler Radar, Wind Profiler with RASS (SODAR), an Automatic Weather Station, GPS Receiver, Radio Sonde, and Middle and Upper Atmosphere Radar. For our purposes though it is the starting point of a journey to the Deep base Bio Lab. Ignoring the "under construction" sign, call the elevator and take to the Shallow base & Submarine elevator nestled in the Sunlight Zone.
While you can teleport directly to the Deep Base lab from here, if you have five minutes it's more interesting to take the Elevator. You descend through the different layers, thru the twilight zone and in to the midnight zone until you reach the base. Beware taking too long, as you might experience an emergency! In the lab are various displays and research areas, and outside you can see some of the native wildlife floating by.
You have to teleport to the next point, the Deep Ecosystem. Here we find all manner of strange animal and plant, and the remains of what has come before. A deep sea submersible films thermal vents, and nearby perhaps some of the oldest forms of life on (or under) the Earth still thrives. From there we can easily teleport back to the Central Hub.
On the way down you might have seen some other complexes as well. The Earth Simulator contains a number of displays with simulations of various sorts, with bank after bank of super computers. There's also the Nautilus & Undersea Design Project. Here there are full size models of Captain Nemo's Nautilus, and other submarines.