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 incredibly difficult to defeat without the use of Power Ups and lawn mowers, since the player is only given Homing Thistle as an offensive plant. Though hordes of zombies are delayed in this level compared to other levels, Homing Thistle often can't keep up with the zombies despite this.
The player must use Sun Bean as a source of sun production, otherwise they'll be too starved of sun to plant anything. This can be really difficult with Octo Zombies and Fisherman Zombies.
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.