The Mk. IV habitat takes shape

As much as I like the Mk.2.6 because it looks cool, it has a few shortcomings. I didn't design LED lights in from the start and the ones I added later were battery powered; There is just a single heating pad and the hamsters fight over it. There's no exercise wheel either, and the weighted base is simply barbell weights bolted to a wooden plank. By designing in all of the desired electrical systems from the start, I can produce a habitat with ample LED lighting and two heated pads, but just a single power cable that penetrates the hull and leads back to the surface. Using a single large enclosure creates enough room for an angled "exercise disc", which serves the same purpose but does not require as much vertical space as a traditional wheel (the same device was used in the Mk.3). However, the most revolutionary addition will be an optional connection for high pressure hose of the type I used for my dive helmet, so that using the same solar/battery powered compressor, I can deploy the Mk.IV habitat to depths of up to 21 feet. This is the limit at which the hamsters will not saturate with nitrogen and therefore will not require decompression. I have many devices at my disposal but a hamster sized decompression chamber is not among them. The deepest deployable depth will be 20 feet, for safe measure. A tremendous depth for hamsters, and probably a record of the kind nobody else will ever see the need to challenge. I don't have access to water that deep, so in all likelihood that particular feature will never be used. But the habitat will be capable of it, should the opportunity arise.