She likes puzzles, so I made her a puzzle box. I invited her on a day out and came to pick her up early in the morning. I handed her the puzzle box and explained she had to solve the Sudoku-like puzzle on the bottom (it's just rows and columns, not squares). Once she had finished the 'Sudoku', she had the coordinates of the locations we were going to visit this day. We used a handheld GPS to find the locations.
The first location was in a nature park with many animals. The coordinates led her to a tree at a lake with a heart carved straight through the trunk of the tree (I did not make that carving myself, it was already there). We had breakfast at this lake.
The next location was at the Batavia, an old ship at a museum at a shipyard. She had to find out the length of this ship to finish the next coordinate.
The next location was at the island Texel, at restaurant "De Zwaluw" (the swallow). It was a long drive and we hanged out at the beach first, then we had dinner at the restaurant.
The next and location was the lighthouse at Den Helder. We arrived there around sunset.
In the mean time my lady already noticed that the pictures on the puzzle box represented the places where we had been this day. I explained to her the flower on the front of the box is actually a combination lock, and each petal had a picture of the places we had been. Now all she had to do was turn the combination lock in the order we had traveled this day. Now the box was unlocked, the leaf could turn to the right and now the nautilus gears on top could be turned, to open the box. The ring was in the compartment on the right.
I proposed to her and she said yes.