What retirement is really like may surprise you and not always in a good way.

Ask retirees what theyve done in retirement that they didnt expect to, and one answer stands out: they spent more money than they thought they would. Nearly one in three retirees say this happened to them, according to a survey released Friday by financial firm Merrill Edge this comes in the wake of a separate 2014 survey from Mass Mutual found that about one in six retirees were surprised by their financial problems in retirement.

7 things that surprise retirees about retirement
Percentage of retirees who say theyve done this in retirement but didnt expect to

Source: Bank of America BAC, -1.10%  

One of the big reasons retirees may end up spending more than they thought they would is because of how much they unexpectedly have to spend on health care, says Aron Levine, the head of Merrill Edge. A couple, both 65, that retired in 2015, will end up shelling out roughly $245,000 thats up nearly 30% over the past decade -- on health care throughout retirement, even though they have Medicare health coverage, according to 2015 estimates from Fidelity.

This high number could result in sticker shock, said Brad Kimler, the executive vice president of Fidelitys Benefits Consulting Services. This may be thanks, in part, to the fact that fewer than one in four people has factored health-care costs into their financial planning. Other reasons they spent more than they expected include higher-than-expected housing and living costs, says Levine.

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Roughly one in five retires was ended up moving in retirement though they hadnt planned to, which, Levine says, may have to do with the fact that they were spending more than theyd expected to and thus felt the need to move to a more affordable place.

On the flip side, many of the surprises giving back (6%), traveling the world (6%), furthering your education (3%) and starting your own business (2%) are things that a lot of retirees say they want, even if they dont think they will do them. A survey by the TransAmerica Center for Retirement Studies found that roughly two-thirds of retirees said that travel was a high priority, 34% said doing volunteer work was, 10% said going back to school was and 4% said starting a business.