In Enchantment Descriptions for Apotheosis, you said Miner's Fervor will effect 1 + level * level * ((sea level - y level) / sea level) for underwater and 1 + level * level * ((sea level - y level) / (sea level * 3)) for overwater.
But it just calculate base on the EnchantmentsLevel(depth) and OriginalSpeed.

That document is not a reliable piece of information anymore (and hasn't been for at least a year, at this point)