Port El Kantaoui
Port El Kantaoui is a tourist complex and upscale residential area that was purpose built in 1979. It is situated 8 kilometres north of Sousse and around 60 kilometers south of Hammamet. It is centered around a marina and is modelled on the more traditional buildings, complete with narrow streets and arches. It is the most expensive neighborhood of Sousse, with an average house costing well over 300000,000 dinar.
Basically, there is the waterfront, with the jetty, and the U-shaped yacht pier, the square in front of the marina and the "gate", followed another square, containing a musical fountain, shops and restaurants. To the north, there is a golf course, and two time-share residential complexes, as well as a number of hotels. To the south, there is an amusement park (Hannibal Park), and two hotels. On both sides of the marina, there are parking lots, and the road separating the port from Kantaoui proper, with the many villas of the wealthy Sousse residents and an Aqua Park.
The town is a suburb of Sousse, so all the tips for getting into Sousse also apply for Kantaoui. If you don't arrive as part of a package tour, from Sousse, you can take a taxi from the train station or the Medina (agree to 5-6 dinar beforehand), the purple tuk-tuk (2-2.5 dinar per person) or the tourist train (2.5 dinar per person).
If you come by boat, you have to report to both the port captain's office in the Marina to be issued a port flag and pay the port tax, and to the customs office. Both are located inside the port, next to the dock. Note that you must contact the port before arrival, since the number of available mooring spots is quite limited, especially during high season. The port tax varies depending on season, and, unfortunately, bribing is quite common.
There are cafes and restaurants lining the waterfront and the fountain area. Additionally, there is a floating restaurant moored in the docks (Neptune VI). Although there are quite a large number of establishments, there is a quite limited choice in the variety of courses on offer - most restaurants will center their menus around fish dishes, with the average menu consisting of about 7-8 fish dishes, 4-5 beef steaks and 2-3 chicken dishes. Expect to pay around 15-20 dinars for a meal for a person. For traditional Tunisian food, there is a quite limited choice, with the only restaurant specializing in such dishes (Restaurant Familial) being tucked away on a narrow street behind the docks. Both restaurants and cafes stay open during Ramadan. In hotels restaurants you will get most likely European food of rather good quality. 
The water in Sousse, Hammam-Sousse and Kantaoui is safer to drink than in most parts of Tunisia, however, it is not advisable to drink it because of the high content of nitrates and chlorine. Bottled water is cheap (0.300-0.600 dinar/1.5 L) and easily available in supermarkets (there are three supermarkets in the port - all located in the square at the Gate of the Port, and one supermarket at the intersection of the two main roads of Kantaoui, next to the entrance in the port) or in the restaurants (1.5-2.5 dinar/1 L).
Lots of restaurants around the harbor serve drinks (you will find them easily, since they all post signs proclaiming that they are the only ones selling alcohol). Most close down around midnight. Most places will only have one type of beer (Tunis brewed Celtia), at around 2,500 dinar per 0.3, and 2-3 types of wine. However, Kantaoui has one of the few Tunisian micro-breweries (Brau Haus), located outside the port, next to the entrance in Hannibal Park and Hannibal Palace, at the crossroads of the two main roads of the town. The only shop selling alcohol is the government owned Magasin General, located next to the Port Gate (open Saturday-Thursday, except during Ramadan, when open only on Monday).
Your choice is restricted to high-end hotels and time-share flats or villas to rent. Most hotels are rated 5 star (comparable with 3-4 star European hotels in both quality and price).