Premise:
"You can find hundreds of caves in the limestone fissures, and some intrepid visitors go spelunking, exploring their watery interiors."
Hypothesis: Some adventurous visitors like to go spelunking to explore the hundreds of caves formed in the limestone fissures.

yes

Premise:
"It is arguably the best in Sicily, an invaluable one-stop crash course in understanding the Greek and other ancient cultures of the city and island."
Hypothesis: It's one of the best in Sicily and offers an understand of Greek and other ancient cultures.

yes

Premise:
"Oh honey, gramps hasn't come up with that yet."
Hypothesis: Gramps hasn't come up with that yet, honey.
yes