Things to do besides science in Reykjavík
Bringing swimming gear to Iceland is not a cruel joke. Due to geothermal activity Iceland is blessed with a lot of warm water and people bath in this - outside. It's a cultural thing. Going swimming really means just sitting in the warm water (for me at least).
Although you can always go to blue lagoon and such, there are community pools that are just excellent. Downtown there's Sundhöllin and closeby the University Campus, where the conference is held, there is Vesturbæjarlaug.
Although it's a bit of a stroll, there's also a geothermal beach in Reykjavík.
A walk in downtown Reykjavík (postal code 101) is nice. The parlement (Alþingi), the Hallgrímms church (Hallgrímmskirkja), the shopping streets (Laugavegur, Skólavörðustígur) and street around it, concert building Harpa and Sunvoyager statue are recommended. A stroll to Þúfa or to the Kjarvalsstaður and the Klambratún park around it can be nice. The panoramic roof of natural museum Perlan can be astonishing on a good day.
The national museum (on the university campus actually) tells a compelling story about the settlement of Iceland and a stroll over Ægissída on a clear day gives a spectacular view (be sure to have a coffee at kaffivest afterwards).
If you have a car to your disposal, the open air museum is fun to visit (and the pool close to it!) and if you really want to drive to the edge of town, then the house of Iceland's sole Nobel prize (Literature) winner Halldór Laxness provides an interesting atmosphere.
There are two hikes nearby Reykjavík you can reach with public transport within finite time (although it'll take a while, 1-1.5 hours one way): Úlfarsfell (go to Skógræktarfélag Mosfellsbæjar Hamrahlíð) and climbing Esjan (Steinn, go to Esjustofan), the mountain opposite to the Reykjavík bay.