Why book a $350 a night hotel room in London when you can have an apartment in a funky neighbourhood for half the price? Or a hotel room in Bali when you can have a villa with a pool in palmy surrounds for $120 a night? Airbnb now has more rooms on its books than the world's largest hotel chains, and there's plenty of blue sky for the service which mates homeowners with travellers looking for a bargain. Despite its global penetration – even Cuba now has 300-plus rentals - only about 10 per cent of travellers have booked through Airbnb, according to a US study. A Goldman Sachs survey found that once they've used it, Airbnb's customers tend to stick with the service rather than going back to hotels.

TRAVEL INSURANCE FOR THE GRACEFULLY AGEING

Over the age of 65 the cost of travel insurance heads skywards. Over 75, a policy for a month away might cost the best part of $1000. There are plenty of older travellers who are fit, sane and sensible, with both the cash and the desire to roam about in the world, yet it seems that the cost of travel insurance policies is predicated on worst-case scenarios. What's needed is a customised policy that takes account of a traveller's health, lifestyle and past insurance record instead of a policy priced on age alone. It's happening with car insurance, so why not travel?

HIDDEN SURCHARGES

The hotel room bargain that cunningly forgets to mention the 20 per cent government tax, the airfare that costs more when you pay using your credit card, the car rental agency that bullies you into a pay-full-return-empty fuel deal when you show up at the hire car desk – these are just some of the ways that providers ambush travellers with hidden fees. They're also growing as more and more players in the industry figure out ingenious new ways to chisel away at your travel dollars. Noxious as they are, they're hard to avoid. If you see a deal that looks too good to be true, it's probably best to run away.

HOT LINES

The smartphone that we cherish and depend on has been hot news lately after several infractions on aircraft, and not just for absurd ringtones but fires. Worst offender is Samsung's Galaxy Note7, which displays an alarming tendency to self immolate when it ejects from a passenger's pocket, falls into the hinged seat mechanism and crushes when the seat back is moved, reacting by smouldering, or erupting in flames. One quick-thinking Qantas cabin crew member drowned a smouldering phone in water, rendering it harmless. The problem is lithium-ion batteries, used almost universally in laptops and cameras as well as in phones. Airlines have guidelines that regulate the carriage of lithium ion batteries, usually available on their website under "baggage information".

TERRORISM

The brutal, murderous cabal that is ISIL is proving almost daily that as it loses the ground war in the Middle East it has both the will and the ability to inflict horror on the wider world, and travellers are in the cross-hairs. One positive - although airports have been targeted, the measures designed to keep travellers safe in the air have been effective so far.

CONNECTIVITY

If letters to the Tripologist are any measure, travellers are less concerned about swapping to a new SIM card to keep in touch overseas. Feedback suggests that global roaming SIM cards designed for travellers are often problematic, and savvy travellers are keeping their usual SIM card in its rightful place. So ubiquitous is free Wi-Fi – in hotels, cafes, restaurants and airports – it's only the traveller who needs 24/7 connectivity who might be swapping their regular SIM card for another.

TOO MUCH LOVE

In an ominous sign, several news sites reported earlier this year that Italy's Cinque Terre was proposing to limit visitor numbers in 2016. The story turned out to be false but it underlines the perils of popularity. Venice, the Spanish Steps in Rome, Angkor Wat, The Grand Canyon, Thailand's Phi Phi Islands and the Kuta-Legian coastline of Bali are just some examples of what can happen when a spectacularly wonderful part of our planet lights up on the tourist map. Global tourism is on the rise, with much of the surge coming from China. Expect some of the places we love most to become a little more squeezy in 2017.

ZIKA RISING

Coming soon to a tropical destination near you, Zika. Thailand, Indonesia, Fiji, Samoa, Singapore, Florida and all of South America apart from Chile, are just some of the regions that have reported cases of local transmission. Evidence suggests that many who contract the virus will show no symptoms and suffer no ill effects, but Zika is a potent threat during pregnancy. Since Zika can be sexually transmitted, the World Health Organisation has recently advised that travellers should avoid unprotected sex or practice abstinence for at least six months after returning from infected regions. Anyone for Iceland?