List of hidden blocks in Paper Mario

In Paper Mario, Mario can discover Hidden Blocks throughout the Mushroom Kingdom. Like regular ? Blocks, these invisible blocks contain coins, items, and even badges. Mario can reveal them by using Watt's field ability by pressing ; however, Mario can still uncover them himself without her, even before she joins his party. All Hidden Blocks are revealed by jumping at them -- there are no Hidden Blocks on the ground that must be hit with the Hammer. Some Hidden Blocks are too high for Mario to hit with an ordinary jump and thus require the use of the Tornado Jump from the Ultra Boots to reveal them (such as four mandatory ones in Toad Town Tunnels leading to Shiver City). Hidden Blocks will never be found in areas with NPCs; as such, they will not be found in shops or houses. If Mario reveals a block containing an item or badge, then leaves and returns to the area without collecting the contents, the block will become invisible again until he does so. Some invisible blocks are used as stepping stones to reach new places or other items. There are 47 Hidden Blocks in the game. This page lists the location of each Hidden Block, the contents, and how to get to them.

Hidden Block count
This chart shows the number of Hidden Blocks for each location, with the total amount at the bottom. Locations are listed in the order the player can visit them.

Trivia

 * Unlike Surprise Boxes in Super Mario RPG: Legend of the Seven Stars and invisible ? Blocks in Mario & Luigi: Superstar Saga which have to be hit twice to collect their items (first time to even reveal them), Hidden Blocks in Paper Mario immediately drop their items as soon as they're hit and revealed.
 * In Gusty Gulch, there is a ? Block containing a single Coin inside a small house with no door one screen east of the Windy Mill. Close inspection through the cracks on the top of the house reveals the ? Block is not invisible.