The main question for a traveller visiting the Comoros is whether to do it quickly (2 days or so in the capital, including day trips on Grand Comore; this will already get you your WHS tick and the nominated site for 2029) or do it well (visit all 3 main islands, which will take you 8-10 days). Many travellers opt for the first option as people returning from the Comoros rarely rave about the country (dirty, nothing to see) and transport options between the islands are not that great. But to do the country justice, you really have to visit all 3 islands, as they differ so much and Anjouan and Mohéli are much prettier than Grande Comore.
Overall, I liked it much more than I had expected: the vibrant culture of Anjouan, the lush landscapes of Mohéli, the food. The people are very nice too, open and often quite chatty in French, Swahili and/or English.
ItineraryD1 - Flight with Ethiopian from Addis. ON Itsandra.
D2 - Day tour of the north of Grand Comore Island, including Lac Salé TWHS, The Dragon's Back and Maloudja Beach. ON Itsandra.
D3 - Flight to Anjouan (30mins). Visit medina of Mutsamudu (WHS). ON Mutsamadu
D4 - Day tour of Anjouan, including perfume distillery Siema town, mountain road and Domoni medina (WHS). ON Mutsamadu
D5 - Amore Comoros Express boat to Mohéli (2h). Lemur watching. ON Laka Lodge, Mohéli.
D6 - Boat trip in Mohéli Marine Park (TWHS), with snorkelling and beach time. ON Laka Lodge, Mohéli.
D7 - Morning forest hike to see Livingstone bats (2h). Transfer to Itsamia and evening turtle watching. ON Itsamia, Mohéli.
D8 - Speedboat to Grand Comore (1h) with Adore Express. Visit Foumbouni town and the medina of Iconi (WHS). ON Itsandra
D9 - Visit Mt. Karthala (TWHS). Afternoon in Moroni (WHS). ON Itsandra
D10 - Boat tour to spot dolphins. End of tour. Visit Itsandra Medina (WHS). ON Moroni.
D11 - Onward flight to Tanzania with Air Tanzania.
Getting there
There aren't many companies flying to the Comoros, and those that do don't have daily departures. For those who travel with checked-in Luggage (I don't) - your bag going missing from your flight is almost routine (Comorians from abroad take huge loads of baggage home). They will send it the next day.
Most of my trip was on a
small group tour organized by Adore Comoros, which seems to be the prime tour operator of the islands. It can be done on your own as well, but logistically it is a hassle.
Visa
Visa on arrival for 30 EUR cash (sticker visa). They do a lot by hand at the airport, but there is a system.
Money
Most was included in my tour. A soft drink costs about 500 CFR (1 EUR), a meal between 10 and 20 EUR. EUR is the best currency to bring as the value of the Comorian Franc is linked to it.
Communications
Few e-sim providers offer packages for the Comoros. I went with Ubigi. Coverage was pretty good (3g only). All hotels, except the one at the Turtle Beach, had decent wifi.