Nothing much new here. Only worries you should have are snakes and plants. You should also begin stocking up on medicines here as you will need them in the future.

The boss on the 30th floor, the Centipede, is similar to, but a bit faster than your encounter in the subway. Casting haste will help you to keep to its side while it's in one piece. Once it splits in four, just use the same tactics as before. Take out one body part at a time. It helps to have a long range weapon as they will move pretty fast in and out of your range. If you have Resist poison on your armor, that will help greatly here too, otherwise you'll be using Medic frequently. When you win, you get yet another key.

Items to be found

Type 64 Defense+?	CR Evade+? Range+?
Monster Cm Jacket	Tool Monster
(2)Tool PPKS Card	Sv Suit 1 M79-5 Tool
B Jacket 2 M1 T-card Offense+?	Tool Super Tool Bullet Cap+?
Mark 23 Super Tool CR Evade+?	Tool Offense+? M870-2