To open the explosive cellars, you will have to use the grenades to open the door of the vaults, which will allow you to access the loot that is hidden inside.
This means it will be important to have grenades in your inventory, so make sure you have enough. Otherwise, you will have to hope that a partner does have and can help you. Just make sure to stay very vigilant, as this can draw enemy attention and if you're not watching you could be ambushed.
This has been our guide on how to open explosive holds in season 8 in Apex Legends, we hope it has been of the greatest possible use, and you have managed to find the opening of the cellars quickly to get the hidden loot.