Spotted tiny pill shaped object that was at commercial flight altitude while sitting at beach.

Was seen first by one member of our party looking directly East asking what it was. My first thought was commercial plane passing at high altitude (often shiny, tiny, and slow moving). Upon closer look, I could not make out the tiny wings that would identify it as a commercial aircraft, but the shine looked to be a reflection of the sun most likely. The best I could distinguish was a very shiny pill shape (oblong oval). Object appeared to be at least 10,000 feet in altitude, but not slowly moving and no jet stream. Just hovering. Then it disappears. Then it reappears (only seconds later) about 60 degrees E->SE at the same altitude. Just hovering around again. It moves again (or appears and reappears) 30 degrees back the same direction and then visibly dives down and disappears under the water (no splash) all still far away from us, but now slightly more visible (still same shape). Reappears East again at high altitude and changes to a very dark color (like it turned over). No longer very bright. Disappears sometime later (we also lost interest).
Beach was not crowded. Maybe 50 total people in a 300 yard radius. My party are all in our late 20s and have good vision. Two work in stem, one works with a nonprofit. Please email me if there’s any questions.
Names:
Rahul Benda
Benjamin Planche
Varia
Unknown