Big Wave Beach - Day 31 is the thirty-first level of Big Wave Beach in Plants vs. Zombies 2. It is a Locked and Loaded level. The tideline in this level is located before the first column, which means that the tide will rise, and water will cover the entire lawn at one point during the level. After completing this level, the player receives a money bag.
This level is relatively easy, due to low zombie density, staggered incoming of zombies and sufficient Plant Food given to the player. Furthermore, Homing Thistles can attack all zombies on the lawn. As stronger zombies only appear later on, there is more than sufficient time to set up the defense.
Using Sun Bean as the source of sun for planting Homing Thistles is difficult, however.
The small number next to the zombie icon means that zombie will always appear in that lane, with 1 being the topmost lane and 5 being the bottommost one.