The summer season is upon us and, with it, school holidays and fun-packed family cruises. On a Mediterranean voyage, ports of call are a fundamental part of the holiday. Some allow for time on the beach, but at many you can visit places that are fascinating and culturally rewarding for visitors of all ages.

There are excursions heavily promoted on board ships and organised by cruise lines. But when should you book their tours, and when (and how) should you explore independently?

To ensure you enjoy affordable and successful days ashore it is essential to do some research before you embark your ship – where Wi-Fi may be unreliable and/or expensive. Here are some pointers.

The pros and cons of a ship's tour

Ship’s tours come with certain advantages: they are easy to book, you’re usually given priority when disembarking and you are guaranteed to be back on the ship by the time it sails. But think before signing up too readily.

You may be familiar with some European cities and feel confident about exploring them independently. And with children in tow you need to be mindful of the summer heat.

Build in time for just pottering and soaking up the atmosphere – perhaps a gelati stop in a piazza or a paddle in a fountain in Rome or a pause to watch the buskers on La Rambla in Barcelona.

Excursions can be expensive and add significantly to the cost of your holiday. To give you an idea: for a family of four a three-hour coach tour of Barcelona with Royal Caribbean International is US$199/£155, and a four-hour walking tour of Venice with Norwegian Cruise Line costs £226.

Barcelona

Location is everything

Establish where your ship is going to dock. Some cruise terminals are close to city centres. In Barcelona, for example, it’s an easy walk or a quick and cheap shuttle-bus ride to the bottom of La Rambla.

The city centres of Monaco and Valletta, Malta’s historic capital, are also within walking distance of ships. In Venice, from the Stazione Marittima port, you may want to take the People Mover (€1.50 one way) to Piazzale Roma, or hop on an Alilaguna Blue Line ferry to St Mark’s Square (€8 one way).

The most cost-effective way to travel the eight miles from Piraeus cruise terminal to Athens is to board bus X80, which stops near the Acropolis. Tickets, which are valid all day across the city’s public transport network, cost €4.50.

Monaco

At some other ports ships dock much further from the cities you may want to visit. For example, Civitavecchia, flagged on cruise itineraries as the port for Rome, is in fact around 47 miles from Italy’s capital. And most cruisers docked at Livorno head for Florence and/or Pisa, 56 and 14 miles away respectively.

In these cases you may prefer to take a cruise line’s excursion (or one with another agent – see below), to be sure of returning to your ship on time. These may be just coach transfers to the city and back, but even so they can be expensive.

Celebrity Cruises’ round trip between Civitavecchia and Rome would cost a family of four $249/£218, compared with a return train journey from the port to central Rome at €30-€104/£26-£91 depending on the type of train.

Rome

Exploring independently

If you want to go it alone in Barcelona, Rome or Venice, download the Telegraph’s free app for iPhones and iPads at telegraph.co.uk/travelapp. It has detailed, expert guides to these cities, with GPS mapping.

Hop-on, hop-off open-top bus tours are a good way to get an overview of cities such as Barcelona, Athens and Nice, and are more flexible and cheaper than the cruise lines’ tours. In Athens, a hop-on, hop-off tour from Piraeus costs €22/£19 (children aged 6-14 €8/£7), booked in advance.

For major sights and museums, and for children’s activities at some, check whether pre-booking is likely to reduce queuing times.

Athens Credit: samott - Fotolia

This is worth doing for the Colosseum in Rome, and for Sagrada Família and the Picasso Museum in Barcelona. And for Florence’s Uffizi Gallery it is virtually essential.

If you plan to spend the day on a beach, it may be much cheaper to take a taxi than a cruise line’s excursion. On Mykonos with Royal Caribbean, a family of four would pay $131/£102 for a round trip to Kalafatis Beach, eight miles from the port. A taxi there and back should cost less than €50/£39. Always confirm a taxi fare before you set off, and ensure that the driver is clear about the return pick-up time.

Alternative tours

An independent agent offering a wide choice of tours in most Mediterranean ports, Cruising Excursions (cruisingexcursions.com) promises to get you back to the ship on time and claims its prices are lower than those of cruise lines.

This can be the case; its Rome On Your Own return transfer from Civitavecchia costs £134 for a family of four – £84 less than Celebrity’s similar trip mentioned above.

With a massive selection of tours and activities, Viator (viator.com) is also worth a look. Although not aimed specifically at cruise passengers, it allows you to filter options for each port to “Shore Excursions”.

You can also filter to “Family Friendly”: a well-reviewed 2.5-hour walking tour of Venice, pitched at families, costs £13.46 a head. Viator is also good for “Skip-the-Line” access to major sights such as the Vatican Museums (pictured below).

For families, arranging a tour with a private guide can be an attractive, if pricey, option, as you can go at your own pace and choose what to see. Viator is a rich source of private tours, as is toursbylocals.com, where the guides are carefully vetted.

When the cruise line’s excursion may be best

Any ship’s tour means less hassle and time spent planning than doing your own thing, but some cruise lines offer imaginative excursions that may be hard, or even impossible, to recreate – such as pizza-making in Sorrento with P&O Cruises, playing gladiator for a day in Rome with Royal Caribbean, and cycling, kayaking and a high-speed RIB ride in Croatia with Celebrity (one of Ben Fogle’s Great Adventures).

And if you want to tackle classical sites such as Pompeii (from Naples) or Olympia (from Katakolon), which are some distance from the ports, a ship’s tour may be best – but compare options offered by the agents mentioned above.