A crash pad — sometimes called a bouldering pad or just "pad" — is a portable foam mattress carried by outdoor boulderers to cushion falls. Pads typically fold in half or thirds for transport and have backpack-style straps for carrying to the boulder. A typical pad is 100 × 130 cm when open and 10–13 cm thick.
The foam is layered: a stiff outer layer to absorb impact and a softer inner core to dissipate force. Higher-end pads use closed-cell foam over open-cell foam for the right balance of firmness and cushion. The cover is heavy-duty fabric — usually 1000-denier polyester or ballistic nylon — to survive repeated drops onto rock and earth.
For difficult or high-ball boulder problems, climbers use multiple pads stacked or arranged side-by-side, with spotters helping direct falling climbers onto the cushioned area. Indoor bouldering gyms have wall-to-wall padded floors, so personal crash pads are an outdoor-only piece of gear. When buying your first pad, prioritise size and durability over weight — thinner pads do not absorb enough force on bigger falls.