On either side of the black plastic tray are round-shaped cavities. The left one has a plastic cover that can be pulled up, and at its base is a screw. What's under there? And what's under the platform on the right side? The car stereo guys are going to put a subwoofer in "one of the cavities in the trunk" and I need to make sure they're not going to block something I need access to. I already had to tell them the spare tire was under the big tray, which they didn't know, so they're making me nervous... thanks in advance.
Check your Owner's Manual. This is explained therein. Left side covers a small storage compartment. I keep my 12v portable mini-compressor and tire gauge used to keep my tire pressures to my preferences. Right side covers the small 12v Prius battery used to start the computers and close the relays which connect the 201v traction battery. There's a lot of other helpful information in your Owner's Manual.
