Giant Secure Containers
Secure containers can be password protected and anchored in space. However, these are 2 separate operations. When I was an empire newb, I made a couple of million by stealing unanchored secured containers in Empire Space. HOWEVER, they were password protected, so I could not open them, although I could scoop them into my cargo bay. What you then do is repackage the container, which erases the password, and the items in the secure container will simply empty into your hangar whether you know the password to the container or not, and the container will be repackaged. When you reassemble the container you will have one that is empty, but that you can assign a password too.
Second, secure containers have Planck field generators inside of them, so that they carry more than they take up. Giant secure containers carry 3900 m3, but only take up 3000. Put 3 of them in an Iteron III with its own cargo expanders, and I can now carry more than 11,700 m3 in it, as opposed to the 5000 something it comes with standard.
Anchoring the Can in Space
When you want to anchor a can in space, you must be at least 5000 meters away from any stationary objects in space, be it an asteroid, a gate or even other secure containers. Cans can also not be anchored within 100km of a station. Once in position, launch (don't jettison) the container, and then right click on it in space (or your overview, if you have giant secure containers visible) and select the password option. It will ask you for the old password, and then a new password with a confirmation field in which you type the new password a second time. If you have no old password or if it is a new can, leave the old password field blank. Once the password is assigned, it can only be opened and have its contents moved by in-putting the password.
If the container is still in your ship's cargohold, right-clicking it will also give you the option to either 'launch for self' or 'launch for corp' in addition to the 'jettison' option. If the container will only be used by you and you don't want others to unanchor it, choose the 'launch for self' option. This will make it unanchorable only by you. The 'launch for corp' option makes it unanchorable only for people in that corp.
The next step is to anchor the container. Do not forget to do this as it kind of defeats the purpose of having an anchorable container in space. If it is unanchored, then anyone who comes across it can swipe it whole or it will despawn. You need the Anchoring skill to do this, but only at level 1, which takes less than an hour to train. The container will take 60 seconds to anchor itself in space. Once anchored, the container will get a small arch icon below the container icon in space. Since Apocrypha, you can only tell if your own can is anchored from this icon. Cans anchored by people in other corps you will have to attempt to open or scoop to tell if they are anchored or not.
Let me repeat this for you faggots:
- Launch for self.
- Anchor your cans.
- Anchor your cans.
- ANCHOR YOUR CANS! AND CODELOCK THEM TOO!
It takes 60 seconds and training a skill to level I. It stops people like me from taking your shit whole in a hauler. Don't be the dumb faggot who loses a pile of money and loot by leaving unanchored, uncoded cans sitting in a belt or on a gate. If you do this, you deserve to have your shit stolen. Even better, put your cans in a fucking safespot and code-lock them.
But how big is it really? Is there a smaller safe inside?
Please note that the ratio of internal space versus external mass is the same regardless of can size. Giant secure containers, as has already been mentioned, take up 3000 m3 of space but store 3900 m3. Huge Secure containers Take up 1500 m3 of space, but provide 1950 m3 of storage. Thus 2 huge containers exactly equal 1 giant in both terms of mass and storage capacity. I personally recommend dealing with giant secure containers when possible due to the fact that you still have to open each one individually once it is inside your hold to get anything in or out of it, and with giant secure containers you will have to do this only half the number of times as with Huge, thus simplifying the procedure and reducing the chance you forget to empty or fill one of them during item transfer.
If you have never used giant secure containers before, you might wonder if it is possible to place them inside of each other like a set of Matryoshka dolls. This is not possible because of some shit involving the "gravitron principles of physics that hold the container together." If it were possible then you would place one GSC into another and have 900 cubic meters of room left. You would then place a third GSC into the second, with another 900 cubic meters available, and so on, granting your hauler infinite storage capabilities, but alas this is not possible.
They do have use in 0.0 space, although mining storage is not really one of them, as you will fill one with Arkanor in only a few minutes with a good mining setup.
I have one set up at safespots in each of the GoonSwarm systems with several thousand rounds of ammo and missiles in them, as emergency backups in case of our stations being camped during defensive op. This allows me to safely resupply myself at anytime regardless of enemy activity in a system
Also you can use them as temporary ratting loot drops that you can later retrieve with your hauler, so you don't have to dock and undock every time your ratting ship's ridiculously small hold gets full.
You can also use them to transfer things to other players in a safe spot like the one above, if for some odd reason you don't want to use contracts, the station trade window, or the market. Some sort of super secret dealy or something. I dunno. I'm just trying to think of more uses for them. I suppose if you want to trade something to a trusted friend, or have some sort of business arrangement setup with someone that involves trading 3900 m3 or less of material/items on a regular basis, and don't want or need the hassle of using contracts or waiting for them to be online, then you could use the can as a secure transfer point that is always online and only accessible to a small number of trusted individuals.
Also, be advised that they are just as susceptible to cargo scanners as ships are, whether or not they are in space or in your hull, and whether or not they are password protected or not. The password is only there to allow you to keep things floating in space and not let anyone else get it.
On a related note, station containers blueprints have been released and allow station containers to be constructed in any station with a factory. These containers are much larger and much cheaper, but cannot be loaded into a ship due to their large size. These are ideal for organizing your items hangar (since you can name them anything you want). It can be a pain to find that one gun out of the 500 items I have in my hangar, but if it is in my hangar in a container listed as GUNS, it would be much easier. I'm gonna set one up for guns, ammo, armor modules, shield, hull, EW, misc and "stuff to melt down", which will help me keep the good stuff from getting mixed in with the dregs when I want to melt down 300 items for minerals. The only drawback, and it can be a substantial one, is that items within station containers do not show up in your "Assets" window. Once you begin to amass huge quantities of useful loot you will probably use the "Assets" window quite often. However EVE Asset Manager, with the use of a FULL API key, can list assets inside station containers.
Obtaining Giant Secure Containers
Giant secure containers are not manufacturable by players, only by NPC stations. They are only available for purchase in Empire stations, and almost always at a set price that hovers around 250,000 ISK.
You can also steal other people's GSCs, though you shouldn't do so if they belong to corpmates/alliance mates and other blues. Occasionally you might find some belonging to neutrals and others, sometimes they won't even be passworded or even anchored! Scoop them to your hauler's cargohold and they'll be yours! If they're passworded then the only way to unprotect them would be to repackage them. This makes the loot pop out into your hangar, and leaves you with a packaged can to sell at a ridiculous markup to dumb goons.
Other Notes of Interest
Giant secure containers can indeed be blown up by hostiles. Since Apocrypha they have greatly reduced HP and a single bomber can take one out in approximately 45 mins. (Personally tested.)
Also, you may find it a hassle to password protect the cans in your hold that you use for cargo expansion, since you have to enter the password each time you want to open the can. I tend not to password protect them, so it only takes a double click to open them for transfer of items.
Keep in mind however, that if you are blown up while transporting them, if they are not password protected people can simply open them up and steal your merchandise. If they are password protected, while they could still pick the can up whole and make off with it, they will not be able to open it up to steal individual things out of it, and the chances of an enemy gate camp having an industrial on hand to pick up your container are quite small, and you should be able to muster a gang up to run off the gate camp and rescue your goods before they have the presence of mind to call in a hauler of their own to steal your container. So I would advise that you not password protect them when using your hauler for mining hauls, but that you do if you are making a pipe run to empire.
Finally, If you do get blown up while carrying a container, if the container is destroyed than everything in it is destroyed as well. If it is not then everything in it will be intact.
Even if the can is anchored in space if you don't open it for 30 days, it will be removed. Unless it is near a starbase (POS). 
Interesting Container "Features"
- You can see who owns a container you find on your directional scanner by right clicking it and "Set Password..." and trying to change it. When it fails it will say something along the lines of "You cannot change the password because this container belongs to XXX."
- If you find an anchored and passworded container and decide to blow it up, it is possible to see what was inside. Before it blows up, get within 2500m of the can and make sure it is selected. The exact moment it blows up, spam click the open container button. The container window will open and you can see everything that was inside (but not take unfortunately). If you only click once it will only stay up for a split second so make sure you spam it.