The Northern Lights are visible from September through March on clear nights, often within a short drive of Reykjavik, and a private guide who knows the forecast and the back roads makes the difference between a real sighting and a few faint smudges on the horizon.
Ice caves form fresh each winter inside the Vatnajökull glacier, and a couple of hours inside one, walls glowing blue where the light passes through, ranks among the more unusual things two people can do together on a honeymoon—though access is guide-only, and slots are worth securing as soon as dates are set.
Reykjavik Pride draws crowds that rival cities many times its size, and the city carries that same openness the rest of the year, gay bars and clubs clustered within walking distance of each other in the city center rather than confined to one district. It gives the trip an easy rhythm: wilderness by day and a proper night out within a short walk of the hotel.
The pace of the whole honeymoon can shift by the day rather than sticking to one register. A morning soaking in a remote hot spring with nobody else around, an afternoon behind the wheel of a Super Jeep on volcanic terrain, and an evening back in Reykjavik for dinner and a late bar—few destinations let couples move between total solitude and city energy this easily within the same trip.