Reykjavík has a tourist economy and a local economy and they overlap less than you would think. The places visitors hear about, the lobster soup spots on Laugavegur and the puffin restaurants near the harbor, are not where Icelanders take each other. Here is the real map.
The pool, always the pool
If an Icelander asks you to meet at the pool, that is a date. Vesturbæjarlaug is the social one. It is small, the hot pots are arranged so you basically have to talk to whoever is in there, and on a Saturday morning you will see half of west Reykjavík cycling through. Sundhöll on Barónsstígur is more architectural, designed by Guðjón Samúelsson, who also did Hallgrímskirkja, and the rooftop hot tubs face south over the city.
Go for an hour, then walk to coffee afterward with wet hair. This is the standard Sunday morning Icelandic relationship-building unit.
Coffee that is not at a hotel
Reykjavík Roasters has two locations, on Kárastígur and on Brautarholt, and both have the slightly serious coffee crowd. Kaffihús Vesturbæjar across from the Vesturbæjarlaug pool is where everyone ends up after the pool. Stofan Café on Vesturgata is the warm, brown, sit-for-three-hours cafe, with sofas upstairs and bookshelves nobody is using as set dressing. Mokka Kaffi on Skólavörðustígur opened in 1958 and still serves waffles with jam and cream that taste like 1958. None of these places are fancy. That is the point.
Hlemmur Mathöll over Grandi Mathöll
Both food halls are good. Hlemmur, in the old bus terminal at the east end of Laugavegur, is the local one. Grandi, by the harbor, has more visitors. If you want the unposed version of a food hall date, go to Hlemmur, get pizza from Flatey and a glass of wine, and sit at the long tables.
Snaps and Sjávargrillið instead of the lobster soup spots
For a proper sit-down dinner, locals tend toward Snaps Bistro on Þórsgata, which has been there long enough that nobody has to explain it, or Sjávargrillið on Skólavörðustígur for fish. Matur og Drykkur in Grandi is the more ambitious choice and the menu is built around old Icelandic recipes done seriously. None of these will appear on the first page of a tourist guide and all of them are bookable a couple of days in advance, not weeks.
Walking, in specific directions
The walk locals do as a date is the path along Ægisíða on the southwest coast of the peninsula, from the Vesturbær neighborhood out toward Nauthólsvík. The water is on your right, the houses are on your left, and there is almost no tourist traffic. It takes about forty minutes to reach Nauthólsvík, the man-made geothermal beach where the water is warmed and you can swim in the Atlantic without dying. Entry is free in summer.
The other local walk is around Tjörnin, the pond in the middle of the city, especially in winter when it freezes and people skate on it. The City Hall has a big relief map of Iceland inside that is worth a look on the way past.
Bíó Paradís for the movie date
Bíó Paradís on Hverfisgata is the independent cinema. They show Icelandic films with English subtitles on certain nights, plus international art-house, plus late-night cult screenings on weekends. The bar in the lobby is a perfectly good place to have a drink before or after, and you do not have to commit to the film if the conversation is going well.
Grocery store run as a date
This sounds insane and it is correct. Melabúðin in Vesturbær is the small, slightly upscale neighborhood grocery that everyone in west Reykjavík has an opinion about. Picking up a bottle of wine and ingredients for dinner together is a real date move here, partly because Icelandic homes are warm and going out in February is cold and expensive. The state-run wine shop, Vínbúðin, is the only place to buy alcohol for home, and there is one on Austurstræti and one on Heiðrún. They close early, by eight on weekdays and six on Saturdays, and not at all on Sundays. Plan ahead.
What locals avoid
The Lebowski Bar, the lobster soup at Sægreifinn unless they are showing a visiting cousin around, anything advertising itself as a Viking experience, the Blue Lagoon for a date, because it is forty-five minutes away and full of tour buses. Sky Lagoon is the local upgrade and worth the swap.
The shorthand: pool, coffee, walk, dinner, drink. In that order, on a Saturday, with one person, and you have done a Reykjavík date the way the city actually does them.