See Merfolk Explorer.

I dislike how you can hose another player with this e. g. Venturing Naturalist activating its ability in response to the trigger of your opponent's Merfolk Explorer. There is no flavor in "using up" the exploration of a land.

Also "second counter" is weird with e. g. Hickory Woodlot. Play that land and reove a depletion counter from it, then activate Venturing Naturalist to put an exploration counter on it...

• It's the first exploration counter.
• It's the second counter in the sense that the total number goes up from one to two.
• It's the overall third time a counter has been placed on the card.

So what shall it be?

As an addendum: I think a necessary fix to the first interaction you should only be able to "explore" your own lands. That is one of the less irritating early variants I checked for Pyrulea as well.

Oh, those are all very good points. Thank you for your input.