Going ashore from a cruise used to involve either a "city panorama" (ticking off sights from a coach); or a "highlights" tour (the cathedral, museum and a souvenir market before piling back on the bus).
But cruise passengers are now younger, more adventurous types capable of finding sites and shops under their own steam, with a map or an app. As a result, the range of excursions is more active and varied. For example, you can take a trip on a MiG fighter, zooming over Russia at twice the speed of sound, whenever Crystal Symphony (020-7287 9040; crystalcruises.co.uk) docks in St Petersburg overnight. For $47,099 (£31,400) you'll fly by commercial airline to Moscow, have a tour, stay overnight, take pre-flight instruction at Sormova Airbase, make the heart-stopping flight, and get a congratulatory certificate. The 11-night summer fly-cruises cost from £3,459 per person.
Or you could try speeding up to a waterfall in an RIB boat on Geirangerfjord in Norway, from £87pp with MSC cruises (0844 561 1955; msccruises.co.uk) on seven-night Scandinavia cruises from £589pp, waterproofs provided. Alternatively, buckle up your safety harness and walk above Stockholm's rooftops for $150 (£100) on the Queen Elizabeth II 14-night Baltic cruise (0843 374 000; cunard.co.uk) sailing from Southampton on 27 July (from £1,699pp).
There's sea kayaking ($100/£67) in Zaton Bay, or mountain biking ($80/£54) in Konalve Valley, Dubrovnik, while sailing on the Carnival Breeze, which launches in June (0845 351 0556; carnivalcruise.co.uk) on 12-night cruises from Barcelona from £559pp, cruise only.
In Jamaica, you can swim in the sea after an exhilarating horse ride on the beach (from £62.50) on Royal Caribbean seven-night fly-cruises from £1,499pp. Princess Cruises (0845 355 5800; princess.com) has sea kayaking (from $99/£66) in the Eagle Islands, Alaska, to spot leaping salmon, bald eagles and seals on its seven-night cruise out of Vancouver (£600pp excluding flights).
Be warned: if you book your shore excursions through the cruise line the ship won't sail until you are back aboard if the tour's return is delayed. But if you go off independently and are late back, the ship will sail without you.
However, there are big savings on scores of excursions when booking with two specialist operators: Viator (020 3318 0421; shoreexcursions.viator.com) and Cruising Excursions (0800 091 8274; cruisingexcursions.com), both of which offer similar trips to those offered on board. They will also refund you if the ship's itinerary changes, and guarantee to get you back on board at the next port of call in the unlikely event that you miss the ship because of the excursion.