The easiest way to Sommaroy is to go to  Tromsø

Domestic: SAS, Norwegian, and Widerøe operate direct flights from Oslo (OSL/Gardermoen) to Tromsø (TOS). There are also good connections from Bergen, Trondheim, and Bodø.
International: The easiest route from abroad is via Oslo (OSL) with SAS or Norwegian. Depending on season, there are also direct flights from several European cities such as Amsterdam, Copenhagen, Frankfurt, Hamburg, Helsinki, London, Munich, Stockholm, and Zurich.

How to get to Sommarøy from Tromsø:
By bus: (Troms fylkestrafikk)
Main line: Line 420 Tromsø - Sommarøy/Brensholmen.
From Tromsø city: Depart from Prostneset bus terminal on line 420 toward Sommarøy/Brensholmen. 
Alight at “Sommarøy” (or “Hillesøy kryss” if you’re staying at the hotel and prefer a shorter walk).

From Tromsø Airport to Sommarøy: On weekdays, typical departures are 12:43, 16:03, and 16:32. 
Typical return departures are 06:30, 07:52, and 13:50. Saturdays: no service. Sundays: typically 16:01 from the airport; return from Hillesøy kryss at 17:40. 
By hotel shuttle or conference bus:
The hotel, in cooperation with the conference organizer, will arrange round-trip transfer between Tromsø Airport and Sommarøy. Further information will be provided closer to the conference. If you need details sooner, contact the organizer or the hotel directly.

If you want to be a tourist, consider travel by Rail, Road or the Coast steamer

The coast steamer: From Trondheim to Tromsø takes 30 h, with stopovers at 12 cities and fisher-harbours, gives you an exciting introduction to coast life and scenery in the region. By many considered a nice coastal cruise.
By road: Pleas set aside several days for a tour from fex Mid-Norway such such as Trondheim to Tromsø. 
Air or rail to Bodø, if you haven't been in North Norway before, a few days through the renowned Lofoten islands will be unforgettable.