ACROSS 

1. What international code flag ‘A’ means (10)
5. Floating object, skippers often talk about picking one up (4)
6. You don’t want to see one of these coming at you, unless it’s the liquorice kind (7)
8. Place in Devon, sounds like a good place for a drink! (4)
9. Don’t let diving make your blood do this! (4)
10. Lumpy sea (5)
11. Marine mollusc, 6 pounds each (5)
12. Grows all over the place, apt nickname for a wimpy diver (7)
15. Safety aide-memoire, from which all good diving should grow! (5)
17. Caught in a current, that’s torn it! (3)
18. Kit left lying about in cars may get... (6)
21. Opening in the side of a boat (8)
22. Sort of dial type thing (5)
23. Big impressive fish, sounds like it comes from Africa (9)
24. Shellfish, not to be confused with the chess piece (5)

DOWN

 2. Greasy stuff much beloved of a few (weird) divers! (8)
3. Give a diver a bit of rope... (3)
4. Hostelry, also a description of someone you might find in one (6)
7. Makes your boat go (7)
9. PADI name for fins (tchoh!) (8)
11. You don’t want to see this floating on the surface (4)
12. A great dive site (so long as its not your boat) (9)
13. Too much of this can ruin the sea state, and get you rejected from the wheelhouse! (4)
14. Since Easter Alice has had trouble with parasites! (7)
16. Pharmaceutical often used by divers, nothing to do with caviar! (8)
19. Set one to catch a mackerel (5)
20. Unit of pressure, a popular haunt of divers (3)