Booked dates ahead of arrival after reading reviews on TripAdvisor and getting a recommendation from someone we knew on the island. The shop is located in town (Kailua-Kona) and easy to find with lots of parking around. My buddy and I checked in the evening before our first dive to complete the paperwork and drop off our gear. As it turned out my buddy left his PADI card at home. It is a card that is old enough that no certification number was on the card, so his number could not be looked up. To make a long story short, the options were for a copy of his card to get faxed to the shop before the dive by a family member who had access to his home, or I would sign a waiver taking responsibility for him. As a tip, I have a picture of my card on my iphone in case I do forget my card.
Our gear was put into bags (bc/reg in clamshell and neoprene in mesh bag) with identification numbers. We dove 3 days and did the manta ray snorkel trip and each time we went out our gear was ready for us.
Having completed the paperwork ahead of time, we had the option of meeting at the dive shop for a ride to the Honokohau Harbor or to meet the group at the harbor. Because Jack's checks first time divers in at their shop in the morning - they say to be there at 8:30 - we opted to meet at the harbor. The staff is very accommodating and allowed us to ride back to the shop on a day when our wives were shopping.
Jack's Diving Locker has several boats, that are large and well maintained with a hot water hose to rinse off. The dive sites we visited were no more than 15-20 minute rides unless, as ours did, the crew takes you whale watching. The crew was knowledgeable, helpful, and personable.
The routine was the same each day: divers arrived at the harbor around 9:00 (they have a small shop at the harbor), the crew was preparing dive gear and when finished, gave a boat briefing before allowing divers to board. The staff/crew are very relaxed and don't rush to get you out and back in. The earliest we entered the water on our 3 days of diving was 9:55. Usually back about 2-2:30. They will give you time to view (and purchase) video that one of the dive masters took on the dives before returning to the shop in town.
Whether you used a computer or not, it seemed to me you could stay down as long as your air held out. As a non-computer diver, I stayed down 53-59 min each dive with maximum depths between 58-80 ft. Our surface intervals were approximately 1 1/2 hrs and included a very good sandwich, cookies, and water/juice. We had 3 dive masters each day and the largest group was 5 divers. No matter which boat (2 ladders vs one) we were on, getting in and out of the water seemed to go smoothly. Best dive of the trip - saw approx. 100 dolphins - amazing!
Also did the night manta ray snorkeling trip. Picked up our wetsuits from dive shop, met at the harbor, and had a great time. The price includes all gear. Can't say if it's best to scuba or snorkel this adventure (we snorkeled because of a non-diver in our group), but sure wasn't disappointed. The manta rays will come very close to brushing against you (and may actually touch you.) Again as with the diving, our crew/guide was very relaxed and time didn't seem to be an issue (we did a little whale watching on the way to the manta ray site.) Our guide was good about maneuvering us to where he thought we would continue to see the mantas. It was a great night and one of the best activities we did on our trip. Cookies and water/juice were provided for snorkelers.
Would recommend Jack's Diving Locker.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.