I'm spending almost a month in Cape Town with my girlfriend, about half of which is going to be spent on a safari. I was hoping to get some non-safari suggestions for the rest of our time there. We're a pretty active duo, so anymore outdoor activities would be great and we're really open to anything else that you think would be worthwhile. Thanks.
I love Cape Town. If your tour doesn't take you to Table Mountain National Park, it's definitely a must do during your own time. I personally like hiking up, having a beer or two at the top, taking in views, then cable car-ing down. The most straightforward way up is the trail at Patterklip Gorge (the trailhead is a couple miles past the tram station). Takes about an hour if you're reasonably fit, maybe two hours for you;) and your legs will definitely be burning at the top, but its a great way to experience Table Mountain.
Table Mountain itself is located directly behind the Cape Town city center (and particularly, the suburb of Orangazicht). The National Park covers the entire Table Mountain Range, which goes all the way down to the Cape of Good Hope. Its all a must do, but the tip above relates to Table Mountain proper.
If you're feeling really adventurous, you should go shark diving. I shark dove in Gansbaai (down the coast to the south) and Mossel Bay. Both experiences were great. Gaansbai is one of the main shark diving areas and you're practically guaranteed to see sharks, but the water can be rough. The Mossel Bay excursion used to be run by a salty guy named Roy and his wife. Overall, it was a more enjoyable experience for me (more mellow, calmer seas, better environment to relax and have a beer while waiting for the sharks), but you also have a higher likelihood of getting skunked (we did, however, see multiple breaching sharks, one of which almost landed on top of the cage). Lastly, they do diving in False Bay (which is very close to Cape Town), but I can't comment on that diving.
For food, Wooden Shoe is a classic, dive, with some pretty mean steaks. Hole in the wall steakhouse. This place Its tiny. Only about 20 seats, is mainly filled with dodgy and semi-dodgy locals. The chef (and owner) is a mountain of a man who is jammed into a small space behind the bar where he operates a grill & stove with expertise. Great random spot for a steak if you're looking for something different (and divey).
If you're looking for something nicer, Salt Restaurant (Bantry Bay) at the Ambassador Hotel in Bantry Bay (one of the beach/waterfront sections of Cape Town... on the way to Camps Bay). Hip, oceanfront, trendy spot. Great food and people watching. Good place for a cocktail too. Quite a scene.
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Since you're active you must must must hike Table Mountain National Park, Lions Head Summit, and Devil's Peak. For Table Mountain National Park there are many different options but the Platteklip Gorge route is the quickest and safest. Take the cable car down at least once and enjoy the view. I also went up Skeleton Gorge through the botanical gardens which are beautiful. The most challenging one I did was the India Venster Route... Amazing but somewhat treacherous. Go with someone who knows the route!
I also did a helicopter tour which was exhilarating and not too expensive. Enjoy!
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I also went shark diving in Gansbaai. It is a great experience and South Africa is probably the best place to do it in the world.
Another great place in Cape Town is Cape Point. Cape Point is actually the location of the Cape of Good Hope. The area is a UNESCO World Heritage site holding a ful 25% of the plant species in all of Africa. You will also see baboons in the area. Stay away from them!
For me Cape Town has some of the best wine tours in the world, if you are as passionate as I am about wine... Plan a tour, do tastings and be sure to include a lunch.
If you are adventurous ... Do a Great White shark dive, there are a number of operations offering trips... Do your homework, I am not sure of the best operator currently... But what a rush, something you will never forget and will talk about forever...
a trip to Robben Island where Mandela was captive is also a MUST do!