The additions of Antarctica specialist Antarpply Expeditions, luxury catamaran operator Golden Galapagos and micro cruise expert Secret Atlas brings ECN’s membership to 26.

Akvile Marozaite, ECN chief executive, said: “ECN provides a hub to share expertise and knowledge in the expedition cruise sector, as well as to help members grow their business sustainably. We wish our new members the greatest success in their new partnership with us.”

Based in Argentina’s Tierra del Fuego, Antarpply Expeditions specialises in taking individuals and small groups to Antarctica onboard its vessel Ushuaia, the second smallest ship operating in Antarctica.

"As expedition cruise has grown, we have been impressed by how the ECN has represented the individual and unique products to professional, international retailers and we look forward to developing our business with them,” said owner Teodoro Gounaris.

Carbon-neutral operator Golden Galapagos, meanwhile, offers its clients luxury tours of the archipelago, while also placing sustainability at the centre of its practices.

Chief executive Luisa Cordova said she was looking forward to working with other ECN members “to make our sustainable practices even better” and to help the Galapagos become a top destination “for luxury travellers who care about the planet”.

Finally, London-based Secret Atlas specialises in micro cruises, taking as few as 12 guests to some of the most remote parts of the world, including Greenland, Svalbard, South Georgia and Antarctica.

"We are excited about the opportunities that ECN will offer, which will not only bring us together with operators who share our passion for responsible tourism, but will provide us with unrivalled access to the UK travel trade and professional expedition cruise retailers from across the world,” said co-founder Michele D’Agostino.

The ECN’s first conference will take place in London over 1-2 October, featuring a full programme of one-to-one trade meetings, seminars, panel discussions and networking opportunities, as well as the first Expedition Cruise Awards.

Broadcaster Monty Hall and former chair of the International Association of Antarctica Tour Operators, Tudor Morgan, will both speak at the event.