Borgarnes in Borgarfjörður is right on the crossroads between the Ring Road heading north and road 54 which rounds the snaefellsnes Peninsula. Close by are Hraunfossar and Barnafoss waterfalls, and one of the most powerful hot springs in Europe, Deildartunguhver. The road up to Langjokull glacier and Húsafell where Into The Glacier operates from. Also, Hallmundarhraun lava field has the great lava tube Víðgelmir, and there are a few lava caves out here but Víðgelmir has been made safe for visitors and you can book tours with a guide.
The geothermal baths at Krauma are here and since there is hot water almost everywhere around here close to the surface there are a quite a few greenhouses in the area as well as swimming pools which can be well worth looking up. The town of Borgarnes is also well known for being a part of the setting for Egil Saga, the story of Egill Skallgrímsson, the great viking warrior poet. The Settlement Center has an exhibition dedicated to Egil Saga and another one the first settlers who came to Iceland and populated the country in the 9th century based on the Icelandic Sagas. The Settlement Centre gives a straight forward and well put together account of these events and for anybody interested in a bit of history and viking lore this is a must. Reykholt is in this area as well, known for being the home of Snorri Sturluson scholar, bard and chieftain, considered the be one of the worlds most important medieval writers, possibly the author of Egil Saga.
Borgarnes is a great stop when heading out from Reykjavík either for a day tour or a longer journey. Around one hour drive from Reykjavik right next to one of the longer bridges in Iceland the town is a service center for most of the area including supermarkets, pharmacies and a liquor store. Even if you are travelling by super jeep on your way to Langjökull Glacier this would still be great pit stop.