S-market

A Solid market! Get smarket!
This place is pretty good- it's got a wide selection of foods, at good prices. It's a good sized grocer in the basement of a shopping center. There's an escalator to get down there, and you have to rent a cart for a Euro. There's no fee for carrying around a basket.
The produce section wasn't so great, but it did have the basic fruits and vegetables at reasonable prices. The dairy section was stocked with all kinds of weird cheeses I'd never seen before. One day when I went, they were sampling up the local cheeses in the aisle. Score!
There's a large bakery section, with a huge variety of rye breads. Go for the ones with lumberjacks on them, or the one shaped like a cat for extra flavor. They also have a big selection of pre-made foods, like cassaroles, fish, meats, sausages, etc. If you wanna grab a bite to go, this is a popular spot. The fish selection was some of the best I'd seen in a supermarket- they must've had salmon prepared two dozen different ways.
The beer selection is pretty primo too! They have mostly canned beers, but with a huge variety of beers from across Europe at discount prices. Many of them are kept cold, but the majority of the craft beers are kept warm. You can buy most of the beers as singles, or as 6+packs, so I chose to jump around with different local(ish) breweries that I'd never heard of. Finland's a cold place, the beer chills really quickly, so don't worry about them being sold warm.
I've never seen such a licorice selection- they had all kinds of the local flavors and varieties. The local specialty is the salted licorice- they have some good examples of this in their huge selection of flavors and brands. It takes up about a quarter of an aisle.
I think you get charged for a shopping bag, so you might try to save by bringing your own. The check-out lines were long, but it seems that they're (unsuccessfully) trying out a self-checkout system. In all, it's a great place to stop by near the train station for fresh or packaged foods!

One of the main supermarket chains in Helsinki. We stopped in on our search for 'tube food' and bottled water among a few other things.

Options are what one should expect from a grocer.

Four stars for price and location. Loving saving money. Especially Euros.