Shalebridge

This location on the map consists of Broken relay tower, Shalebridge Tunnels and Shalebridge Hills. The latter two are rival ant colonies.

Shalebridge Tunnels
'''Important: Do NOT search any of the invader ants, as it will trigger a message that makes the game freeze upon reentry of the tunnels. This includes loading a save made within the tunnels, and it is thus possible to make a playthrough impossible to continue, should all saves be made within the tunnels after receiving the message, unless there are backup saves.'''

Shalebridge Tunnels is a small cave system that is home to a small, friendly mutated ant colony. The entrance is to the north from the broken relay station located just below the hill and resembles a circular plate or cover surrounded by glowing mushrooms.

When the player enters, the smaller friendly ants are under attack from larger, more aggressive ants. The larger ants will attack the player and can be killed to protect the colony. The larger ants will not be here if you have already killed the queen in Shalebridge Hill.

There is a dead Ant Researcher in a pool of water near the eggs that has a Big Book of Science on his corpse. The Ant Researcher respawns every 73 hours (with a new book). Usually he's alive, fighting an ant, but you can kill him with no karma penalty and take the book from his corpse.

If you inspect a nearby ant egg-sac, the option to inject a stimpak is given. There is an Ant Compost Heap with some Ant Nectar in it and it will replenish faster upon killing Ant Queen in Shalebridge Hill.

If you kill and then search one of the larger ants you will get this message:


 * It appears that these ants are from another ant colony. Perhaps attacking this rival colony would help the forager ants survive.

Hidden Tunnels
On the local map there are what appear to be openings to tunnels that are not found when you go to that point on the map, two of these make a complete small loop, and another appears to be a long tunnel along the outside of the cave to the left.

Climbing up on the boulders to the left of the first two pillars in the first large room near a small puddle, you will find you can continue to walk up the boulders, staying close to the wall. You should be able to get in on the far left side of the opening. You may need to crouch to get in, but once in you can stand up - even Fawkes can get in here. There appears to be another opening on the left, but you cannot get through this one. Straight ahead or to the right is one of these small loops, it is however a closed loop and does not lead to the long tunnel on the left. The opening to the left of this hidden entrance can be accessed partly from the opposite side - similarly by bouldering up. This is directly ahead of the entrance to the Shalebridge tunnels at the south end of the small loop. There is another small opening that appears to be the entrance to the long tunnel below it, on the ground level. You cannot enter either opening, even when crouched. A similar inaccessible opening is at the very end, centered in the back wall of the last cave with the eggs and the compost pile.

Shalebridge Hill
This colony is just north of Shalebridge Tunnels. There is not much here except Ant Workers, Ant Soldiers and an Ant Queen. An interesting way to get rid of her is to try remain as high as possible and cripple her antennae, causing her to frenzy. She will start attacking her former fellow ants who have numbers on their side, so she will get swarmed and die. A flamer will also work quite well.

Bugs

 * The Queen Lair has only minor loot, 10mm Pistol, 10mm ammo, shotgun shells and 5.56mm ammo. The 5.56mm ammo is bugged however so don't try to pick it up or you will experience critical error. (No visible error seen when picking it up in the PS3 version or 360 version, however, it seems to crash the application consistently for some PC users.) A Scoped .44 Magnum with ammo can be found near a rotting Brahmin corpse.
 * In the PS3 version, NPC Star Paladin Cross won't follow you into either the tunnel nor the hill. However, she will suddenly appear inside after you travel in a ways and have no problems following you after that. The NPC, Fawkes, also displays this behavior, which puts forth the possibility that any of the humanoid PCs will behave in this manner as well (Charon should follow you just fine).
 * There are also Mentats, Metal Armour and a Jet in a pile of bones, through the tunnel on the right as you enter the Invaders/Queens Lair. (You have to jump over the rock to get through the tunnel)
 * After injecting the stimpaks into the hive and then killing the Ant Queen, there is a chance you cannot enter the tunnel anymore. This issue has been spotted on Xbox360 versions. The game will freeze on loading screen when you attempt to enter the tunnels after the enemy queen is dead.
 * The trigger for this bug appears to be "inspecting" (attempting to loot) the invader ants' corpses ("It appears this ant is from..." message). Upon exiting the tunnels, it will always freeze upon returning. Best course of action is to NOT interact with the corpses when killed.

Loot outside cave

 * Quite a bit to the east of Shalebridge Tunnel entrance (Due south of the train wreckage, across the irradiated mudhole) there is an ant egg clutch (it is on the other side of the rocky hill) with a copy of D.C. Journal of Internal Medicine and a Stealthboy underneath the dead Raider. (See Abandoned Car Fort.)