Unique proposal ideas include a scavenger hunt and a return to the place where the couple first met. These ideas incorporate fun and adventure into the proposal without being overplayed, as in a stadium proposal.
A fun and unique way to propose marriage is for the one proposing to set up a scavenger hunt for his fiancée. The hunt incorporates a list of items that have meaning to the couple and culminates with the presentation of the ring. For example, one clue might say to go to the spot where the couple shared a first kiss, and the hunter would know immediately to head to the mini-golf course. She would find the next clue waiting there.
Another low-key yet unique way for someone to propose is to suggest, possibly for a date celebrating an anniversary or other special occasion, a return to the place where the couple first met. If they met at McDonald's, for example, they could return to that location, eat at the table where they shared their first meal, and the one proposing could pop the question during the meal.
Someone planning to pop the question can think of more proposal ideas by considering his partner's unique interests and incorporating one or more of those interests into the proposal.