Wouldn’t the more logical first approximation be to bury them underground, and then progress towards (perhaps) placing them in or near the ocean (obviously, within sealed containers, yadda yadda, salt corrosion, yadda yadda, inhospitable environ yadda yadda makes Poseidon angry).

I like the “yeet them into the sea” idea conceptually because (1) yeet them into the sea (2) in theory, you could power them via tidal/wave/OTEC (3) water cooling.

Seems…too obvious. There’s probably a good reason (or bad ones - $$$) why this hasn’t been tried yet. But I bet those reasons are eminently more solvable that “send em into space”