For those intrigued by the OP g2's report, I offer some recent and additional information based on my recent trip at the end of February. I will cover the various topics in more or less the same order as followed by the OP. Warning: this is looong.
FLIGHTS: There are now weekly flights from and to Capetown on Saturdays. The flights from and back to Johannesburg are on Tuesdays. Not sure if Capetown is a seasonal addition or will remain for the foreseeable future. But having this option opens the possibility of doing your trip in more than just one-week blocks by perhaps flying out of Capetown and flying back to Johannesburg, for example.
The flight to St. Helena takes a little over 6 hrs due to the obligatory refueling stop in Walvis Bay in Namibia, whereas the return flight only takes a little over 4 hrs because it skips the refueling stop. This was explained to me as due to the need to have enough fuel to divert to Ascencion Island in the event that wind and weather made a landing in St. Helena a bit risky.
WATER CONDITIONS and DIVING: Be it La Niña or whatever, I saw 73-75 degree water temps throughout my trip in which I did 4 days of two-tank dives in the mornings and 5 days of whaleshark snorkeling in the afternoons. I used my last day to pack in an all-island tour and found it to be very interesting and enriching. That gave my dive gear more than a full day to dry. Conversely, air temps were very comfortable high 70's to lo 80's with hardly any humidity, which, I was told, is odd for their summers.
On the other hand, there were some serious northerly swells the whole week I was there. I was told that this happens perhaps 10% of the year. Since the OP most likely used the same dock area that we used for going out, I am sure that he can imagine how hairy it can be when 5-6 ft waves are coming in, and you are trying to either board or get off the boat. In fact, a more quantitative illustration of how fierce those swells were was that when the waves broke against the waterfront wall, the resulting water breech shot up some 40 feet and landing clear across the entire width of the street. Fortunately, the boat captains are good at observng the cycle of those swells, bringing the boat to the dock when there is a temporary lull. Still, not for the faint of heart.
My initial choice was to dive with the same Dive St. Helena that the OP used, but they were booked up well in advance by an European group that happens to always go the end of February. So I went with Sub-Tropic Adventures, was not disappointed, and would wholeheartedly recommend them except that the owner is in the process of selling in order to move to the UK. I did meet and speak with Craig Yon, the owner of Dive St. Helena, and he was most helpful, friendly and very professional.
RESTAURANTS: Ann's Place was indeed an excellent choice for dining - when it was not all booked up. It is best to make reservations if on weekends. They have a little bit of everything at reasonable prices and very friendly staff and owners. On days that I wasn't particularly hungry, I just asked for three servings of their tossed salad, which was great.
There is an Asian restaurant, the Orange Tree Oriental Restaurant, a couple of doors upstream of the Mantis Hotel entrance. It is a bit pricy (avg £15 ) compared to all other restaurants but on par with prices I see for Chinese food here in the US. The servings are huge and the food was quite good considering where we were. The only caveat is that it is a one-person operation: Gilbert is the host, the chef, and the dishwasher. If you wish to try it out, reserve in advance and better yet, also order in advance. That way, your food is already cut-up and prepped and ready to be cooked the moment you arrive.
I stayed at the Mantis Hotel. The restaurant there is also quite good with good ambiance, friendly staff and also a littl eof everything for every palate.
I also tried the pizza place one night for a change of pace. And that is all that I though of it - a change of pace. When walking towards the waterfront, they are on the right after going thru the arch, with the St. Helena Coffee Shop across from them. They are only open Thursday to Sunday, I think, and they get a looot of take-out orders. So expect waits in excess of an hour before you get your food. They only have two park bench tables for eating in.
FOOD: There are four foodstores, all within easy walking distance one from the other: The Star, Atlantic Store, Thorpe, Rose and Crown. Aside from some limited produce grown on the island, food comes by container ship - once a month!! That may be why the OP found the stores to be rather lacking. The only things I found plentiful and always in stock were locally-grown potatoes and onions.
When I was there, the container boat was actually anchored in the harbor but could not dock to unload due to the afore-mentioned heavy swells. Hence, the only fruit I had all week was canned fruit cocktail at the breakfast buffet at the Mantis. The joke going around while the boat remained unloaded day after day was the stress and consternation building up in the general population becausue the island was quickly running low on...........beer.
MONEY: I chose to get British pounds at a Travelex ATM at Heathrow, which is where I made the connection to fly to Capetown. The exchange rate was awful but there wasn't much of a choice. I believe that Thorpe was the one grocery store that accepted credit cards. I did settle my bill with a credit card when I checked out of the Mantis, which raises the possibility that the restaurant might take them(?).
THE ISLAND OVERALL: It is indeed an interesting island, all packed into a 44 sq. miles with about 4000 residents. Definitely worth planning a day off to do a land tour. Aaron's Adventure Tours was excellent. The island is very much steeped in history, just as the narrow roads that criss-cross the mountains are steep. As the OP, said, it is an extremely vertical island, and the views from atop are impressive - when you are not in the clouds.
In downtown, there are the 699 steps (close to a foot-high each) of Jacob's Ladder to climb at a roughly 40 degree angle for a great view of the harbor and the town of Jamestown. It is quite intimidating when viewed from the bottom. Not something to do after diving.
There are all the Napoleonic historical sites from Napoleon's exile and eventual death and burial on the island.
The world's oldest ever tortoise, Jonathan, lives here. 192 years old. To see him up close, you need to schedule your tour for Tuesdays or Thursdays.
St. Helena coffee is one of the most expensive coffees in the world - in my opinion, probably more so due to limited supply as opposed to amazing flavor.
The locals wave to not just people driving by but also to pedestrians. This just adds to the charm and quaintness of the island.
There is some uniqueness to the whalesharks here. Some are so slooow that you can literally swim circles around them. Everywhere else where I have seen them, it is always us divers and snorkelers chasing them. But in St. Helena, some of the whalesharks seem to get a kick out of chasing us.
What was also refreshing about everywhere we dove or snorkeled was that we were the only divers or snorkelers at the chosen site. It is therefore apparent that the two dive operations, which occupy side-by-side spaces at the waterfront, coordinate their trips such that it is only one or the other at every site.
Final words in this lengthy narrative: I also did the obligatory overnight safari out of Capetown in addition to doing an all-day land tour of Capetown. I was already there, so no regrets about spending a little more rather than feeling oblgated to come back some day.
So, indeed, a trip like this coming out of the US can get mighty expensive. But I came home happy and fulfilled, having met some wonderful people, having seen most of the highlights and some things I'd never seen before, both on land and in the water. St. Helena being in the middle of nowhere, there are quite a few endemic species of fish. Just seeing those made my trip.
