Lindblad runs designated family departures with a naturalist dedicated to the younger guests, and they are the best thing in expedition travel for children.

On these sailings there are other kids, the activities are pitched for them, and there is a structure that lets parents do the harder hike while the children do something else.

Galapagos and Alaska are the two I recommend most. Galapagos because the animals do not run away and a child can stand three feet from a sea lion, and Alaska because the scale of it does something to people.

They sell out. Family departures in particular go a long way ahead. If you are targeting a specific summer, book the previous year.

This is the region Lindblad are most identified with, and that is not a marketing claim. Lars-Eric Lindblad ran the first tourist voyage to Antarctica in 1966. Everyone sailing down there now is working in a category he opened.

Four National Geographic ships go south, carrying between 102 and 148 guests. That number matters more than anything else in the brochure. IAATO rules cap landings at one hundred people ashore at a time and bar ships carrying more than five hundred passengers from landing at all, so a ship this size gets everyone onto the continent instead of rotating you through in shifts.

Voyages run roughly eight to twenty five days, most falling between ten and eighteen. You can sail the Drake Passage from Ushuaia or fly over it from Punta Arenas, trading four days of sailing for a two hour flight. Zodiacs, kayaking, photography instruction and the parka are in the fare.

For Antarctica, the Arctic and Greenland they publish a minimum age of four, younger than most of the field. The full Antarctica guide is here if you want the season, the costs and the other ships side by side.

Small, purpose-built or purpose-converted expedition vessels carrying from a few dozen to around a hundred and fifty guests depending on region.

Comfortable rather than luxurious. Good cabins, decent food, a lounge, a small gym. Nobody is booking Lindblad for the interior design and the company would not claim otherwise.

What the ships have instead is equipment. Zodiacs, kayaks, undersea cameras, remote vehicles, snorkelling gear, and on some vessels a hydrophone so you can listen to whales.

It is physically active. Wet landings, zodiac transfers, uneven ground. Anybody with serious mobility limitations should discuss it honestly first.

Itineraries change and you must be relaxed about that. If a fixed plan is important to your family, expedition travel will frustrate you.

And the weather is the weather. Polar regions especially. Pack accordingly and adjust your expectations before you go rather than on day two.