text: Benthic Explorers checks the effects of all mana-producing abilities of the land untapped to pay its cost, but it doesn’t check the costs of those abilities. For example, Vivid Crag has the ability “{T}, Remove a charge counter from Vivid Crag: Add one mana of any color.” If you untap a tapped Vivid Crag an opponent controls while paying for Benthic Explorers’s ability, you can add one mana of any color to your mana pool. It doesn’t matter whether that Vivid Crag has a charge counter on it.