This seems strong, like super strong, I cannot fathom a reality where this isn't broken

Gosh, yes. Literally the only penalty is that you cannot play it on turn one. So long as you have another land it's just flat mana ramp.
And that's not even getting into the potential of "And in response, I drop a secret cove and now I can afford..." Even if I was playing another colour, even if it sacrificed itself at end of turn it's still a +two-mana ritual.

As it is, this is way way too good. I get that you seem to want to play with fun effects on lands; but there is, sadly, a reason why their effects are very weak. Which is that there's almost no cost to putting them in your deck, since they replace land slots you already had to dedicate, and they don't cost any mana.