With the second half of the third season of The Walking Dead set to premier on Sunday (9/8c on AMC), we are reminded of the importance that the topic of long-term sustainability -- food, water, etc. -- plays, especially when it comes to dealing with roaming hoards of living dead. Rick Grimes & Co. have made use of a number of locales, jumping from a quarry campsite to Hershel's Farm and now, as we saw through the first half of Season 3, a supermax-turned-Marriott known as "The Prison". Not all of us have off-the-grid living options at our fingertips, but fortunately there are plenty of homes on the market to satisfy such specific needs as sustainability and zombie defense, and a guy like me willing to put in the legwork to find them for you.

But before we jump right in to our fine list of sustainable, zombie-proof outposts, there is one other zombie-related topic that needs addressing: mainly, the idea that zombies can walk underwater or maybe even swim. In our last zombie-proof fortress roundup, many of you seemed convinced that zombies can, in fact, walk underwater. A few even surmised a far-fetched Land of the Dead scenario where zombies develop cognitive skills. As theresident living dead authorityin these parts, I can assure you that, save for a shallow, non-moving body of water, zombies will NOT be strolling into the Atlantic and walking their way to Europe, China or some other continent, let alone swimming anywhere. I would be far less concerned with zombies walking underwater and more concerned with the possibility of a zombie falling into water, getting hold of and biting a fish (or shark!), thus creating a ZOMBIE FISH (or ZOMBIE SHARK! zOMG!).

With that out of the way, let's jump right in to our tour of sustainable real estate - castles, islands and more - for when those with an unquenchable thirst for human flesh come knocking on your door.

Castle Post in Versailles, KY

Price: $30 Million

The Skinny: The first commandment of zombie defense in the wake of an undead surge is fortify, fortify, fortify, and you would be hard-pressed to find better fortification than at the stonewalled Castle Post in Versailles, KY. In terms of The Walking Dead, this is about as close of an equivalent of 'The Prison' as you are going to find. You have your outer defense wall, spires and battlements for guarding against the scourge and rouge outliers alike, as well as plenty of room for growing crops within the perimeter. Then there's the castle itself; a towering three-story structure made of stone, boasting 50 rooms, eight towers and rooftop shuffleboard.

Bonus Zombie Defense Feature: A cache of medieval weapons and armor, including, but not limited to, swords, battle axes, helmets and chainmail.

Urraca Green Compound in Mosca, CO

Price: $2.36 Million

The Skinny: There is remote living and then there is thousand-acre-property-that-backs-up-to-a-National-Park remote living, which is why we turn our attention to The Urraca in Mosca, CO. While it's not totally impenetrable, the green compound is isolated and alone in the wilderness, AND it has everything one needs to restart civilization in the wake of its gruesome, untimely demise. Classified as a nature conservancy, the property boasts various living quarters and workshops, secure areas to grow crops and multiple sources of clean water. Plus, there's a forest chock-full of harvest-able plant life and kill-able critters.

Bonus Zombie Defense Feature: Extensive solar paneling covers the roof of the 5,200-square-foot home, essentially freeing you from the burdens of a "conventionally-derived electric grid." It's a pretty nice feature to have for when throngs of walking corpses overrun your city, disabling its power infrastructure.

Wolf Trap Lighthouse in Chesapeake Bay, VA

Price: 249,500

The Skinny: According to the listing, "Wolf Trap is a cassion lighthouse built to withstand extreme weather" -- and from the looks of it, HORDES OF THE UNDEAD. You basically have your own outpost against the world on your hands with this bad boy. Even if a zombie somehow manages to float over or perhaps ride one of his undead buddies like a para-sail, there is no way for the walking corpse to actually climb and penetrate the the lighthouse. Learn how to fish and watch a few Bear Grylls videos on how to catch condensation with a tarp, and you are good to go with this aquatic fort in Chesapeake Bay.

Bonus Zombie Defense Feature: A working lighthouse light. It may not be an actual zombie defense feature, but you could totally rig your own bat signal with a roll of duct tape or whatever is on hand, and that, my friends, would be freaking awesome.

Bucks Walk Timberframe in Black Mountain, NC

Price: $1 Million

The Skinny: Old man Hershel would be proud of this fine backwoods outpost. They might have thought they were designing their own eco-friendly compound in the hills of Black Mountain, NC, but what they ended up with is about the closest thing to a model for sustainable living in a world ruled by the undead. Beyond its incredible vantage point and solid timber-frame construction, the trio of residences that make up Bucks Walk can be powered by its system of solar panels. Also included is a generator and potable water supply, which provides heat and potable H2O to complete the off-the-grid trifecta.

Bonus Zombie Defense Feature: A greenhouse with its own cistern-supplied water source and solar rigging allow you to grow fruits and vegetables year-round, negating the need for dangerous foraging trips into your local zombie-infested supermarket.

Tavern Island in South Norwalk, CT

Price: $12.9 Million

The Skinny: They claim it's just a "Tea House," but my gut tells me they're serving up something a little stronger than leaves soaked in hot water on a place called Tavern Island. And what better way to calm the nerves during the zombie apocalypse than a tipple or two? Besides Tea House elixirs, the Norwalk, CT island boasts 3.5 acres to cultivate crops and sustain the clan, along with a pair of residences, a deep-water dock and a harbor with a stone sea wall.

Bonus Zombie Defense Feature: Protect your island from enemy raiders and possible infected with an antiquated cannon defense system.

Old Titan Missile Site in Sturgis, SD

Price: $275,000

The Skinny: It's a former Titan missile manufacturing site with nearly 58 acres of Sturgis, SD land. A metal shop with living quarters, a 100-gallon above ground cistern and two sewer lagoons allow you to craft next level zombie weapons while digging in for the long haul.

Bonus Zombie Defense Feature: The entire joint is enclosed by a 10-foot chain-link fence with razor wire. Plus, the potential for unearthing a lost rocket or two.

Sportsman's Outpost in Cambridge, MD

Price: $30 Million

The Skinny: Another property that falls into "The Prison" category, this particular dandy is the outdoor equestrian/hunting wet dream of ahedge fund mogul. This is a particular case, well, a particular case with zombies, where a Wall Street billionaire's mind-numbing level of extravagance is a welcomed thing. An entrance built to withstand King Kong starts things off on the right foot at the 6,250 acre estate and it just keeps on getting crazy better from there. An Adirondack-style lodge the size of a small hotel obviously takes center stage, but other all-star highlights include a dog kennel, riding ring and horse stables, indoor tennis and basketball courts, and the list goes on.

Bonus Zombie Defense Feature: Nine square miles of carefully managed hunting and fishing areas fully stocked with wildlife and game native to the area.

Historic Civil War Fort & Immigration Center in Portland, ME

Price: $4.85 Million

The Skinny: It's not the impenetrable stronghold that is Alcatraz Island, but House Island in Portland, ME definitely has new world outpost possibilities for rebuilding in the age of the walking dead. Previously used as an immigration quarantine station, the historic site features a brick-lined 19th century fort, three cottages, two deep-water piers and plenty of room to move --24 acres to be exact.

Bonus Zombie Defense Feature: Remnants of an immigration quarantine station are the perfect staging ground for screening possible infected.