One of the many perks to visiting or staying in Cape Town is that you're never far from access to the water. Here are some of my favorite working harbors to view colorful fishing boats, sea lions, and places to pick up fresh seafood for dinner.
Hout Bay is quite small, but worth a stop for a meal before or after continuing on Chapman's Peak Drive (one of the best scenic drives in Cape Town). The Bay Harbor Market is a great place to grab a bite or buy a souvenir or two to bring back home. Look out for sea lions in the shallow areas to either side as you stroll up and down the pier.
A sunset cruise can easily be booked from the V&A Waterfront for a nice relaxing trip into the harbor and beyond, usually down to Camps Bay and back (depending on wind) in about an hour. The crew will have a blanket on hand, but I also recommend taking a jacket. Once the sun goes down and the wind picks up, it can get a bit chilly.
Walking left out of the Kalk Bay Metrorail station and down the main road will eventually take you to the village's harbor entrance. From the white tablecloths of Harbor House to the picnic tables at Kalky's, there are several seafood restaurants down at the pier to fit every budget. A few local vendors hawk beaded trinkets and paintings, while fishmongers fillet the day's catch right in front of your eyes. Expectant sea lions swim up to the pier walls as seagulls circle overhead looking for their discarded scraps. Colorful boats bob and sway in the gentle waves, making this a great place to take photographs and enjoy the local fishing culture for an afternoon.