Answer first: it is an easy second day. Spend a morning on the Conero coast, then drive about an hour to the caves.
The coast
The Due Sorelle beach below Monte Conero has no road access: you go by boat or kayak from Numana, Sirolo or Marcelli, and there are no services there (italia.it). Take water and food. GetYourGuide lists a Monte Conero e-bike tour and a Portonovo bay walk (few reviews).
The caves
75 km from Numana, about 56 minutes. Choose a later cave slot and book tickets.
Stay
Frequently asked questions
How far is the Conero coast from Frasassi?
About 75 km, 56 minutes from Numana (Rome2rio).
Can I walk to Due Sorelle beach?
No. It is reachable by boat or kayak only, from Numana, Sirolo or Marcelli, and has no services.
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