Each day, Groupon features an unbeatable deal on something to do, see, eat, or buy in select cities. By promising businesses a minimum number of customers, they’re able to negotiate discounts you won’t find anywhere else.

Today in Boston for instance, they offered 53% off a Beginner Kayaking Class at Valley Mill Kayak School. In order to get the discount, 30 people needed to buy the coupon in order to qualify. When I checked, they were already at 77.

So far, Groupon is available in Boston, NYC, D.C., San Francisco, Los Angeles, and Atlanta.