You'll find yourself parked right at the shore of the P2 Lab. There's a Team Plasma Grunt outside, although he won't fight you, don't worry. Inside of the building, you can pick up a Dubious Disc, which can be used to evolve Porygon2 into Porygon-Z when held during a trade.
The Genesis of Genesect!
If you've received your Genesect from the Wi-Fi Mystery Gift event that took place from the release of Black 2 and White 2 until November 11th (or the Wi-Fi event from the Japanese versions), you can take it here to trigger an interesting event. You'll find a Scientist who goes on about Genesect and will then battle you. He just has a Klink L34 and a Klang L34, but after beating him, he'll give you the Shock Drive and Burn Drive if you're playing Black 2 or the Douse Drive and Chill Drive if you're playing White 2.
These Drives can be equipped by Genesect to change the color of its pack thingy on its back as well as change the type of its Techno Blast attack if it's held by Genesect. You won't be able to obtain all four drives unless you trade between versions, though.
Perhaps most important is the plank leading onto the docked Plasma Frigate! Assuming you're fully healed and ready for a challenging fight, you should definitely head on inside.