But even if you are not Jason Bourne - who needs somewhere to store his multiple passports, guns, and stacks of foreign cash - safe deposit boxes can be a useful spot for your family heirlooms and critical documents.

One problem: Some of them are going away.

Banking giant Chase has discontinued offering safe deposit boxes for new customers, although it is maintaining them for existing clients. Other institutions have also pulled back on offering safe deposit boxes, such as Capital One, HSBC and Barclays.

"The hottest story right now is that banks are eliminating this service," says Dave McGuinn, president of industry consultancy Safe Deposit Specialists in Houston. There is both the significant physical expense of offering secure storage for valuables along with the potential legal liability if something goes amok, McGuinn notes.

Combine that with the macro trend towards online banks and away from brick-and-mortar locations, and safe deposit boxes have become more challenging to find.

But apparently some consumers still like and use them - judging from the waiting lists that in high-demand locations can extend up to five years, according to McGuinn.

"It is not just valuables, but also important documents like birth certificates and passports that are advisable to store off-site to safeguard against theft or fire," says Peter Palion, a financial planner with Master Plan Advisory in East Norwich, New York.

So if safe deposit boxes become endangered, what exactly should people do with objects and documents that are too important to be just lying around the house? A few thoughts from financial experts:

SHOP AROUND

Even if one major bank is not offering safe deposit boxes to new customers, that does not mean others are not. Wells Fargo has them available for rent at most locations, according to a spokesperson. You do have to bank at Wells Fargo, with annual pricing typically around $45 for the year.

Meanwhile, Bank of America still has them in 80% of its financial centers, with two million clients using the service.

GO DIGITAL

You will not have to worry quite so much about physical documents, if you have them filed away in digital form. If safe deposit boxes are becoming scarcer, this could nudge you in that direction.

"Tools such as Everplans or DocuBank can be used by advisors and estate attorneys to assist clients in having a electronic document storage system," says Aaron Clarke, a financial planner in Gainesville, Virginia. "This will help organize documents and guidance while giving heirs access to this information electronically, and uniformly."

IMPROVE YOUR HOME STORAGE AND SECURITY

There is no law saying that you must keep your most critical stuff off-site. But if you are keeping treasured items at home, you should make sure to keep good care of them.

That could mean a modest safe, along the lines of those you see in hotel rooms, which can be had online from brands like Honeywell for $100-$150. Just remember that home security is nowhere near that of a bank, with its vault doors, closed-circuit surveillance, restricted access and sophisticated alarm systems. McGuinn himself found that out, when his home was burglarized and his home safe smashed to pieces.

For grant strategist and fundraiser Allison Markin, her favored option is to keep her must-have documents in a fireproof bag.

"I'm in a fire and flood zone in British Columbia's Okanagan Valley, and it is part of my 'bug out' emergency evacuation plan," says Markin, who keeps a list of important items to grab and go on her phone.

GET INSURANCE

You might think that if your stuff is stored safely in a bank vault, there is no real need for insurance. Not so. Bad things can happen at the most secure facilities - fires, floods, theft, or just plain old human mistakes and poor record-keeping.

One method is to get a "personal articles floater" as a rider on your homeowner's policy. Or you could get a dedicated policy, through specialty firms like Safe Deposit Box Insurance Coverage (https://safedepositboxinsurance.com/).

"You should absolutely get insurance on the items in your safe deposit box, just as if those items were at your own house," McGuinn said.

(Editing by Lauren Young and Aurora Ellis; Follow us @ReutersMoney)

By Chris Taylor