Something To Declare: Medellín; Thailand; Southern Railway; Amsterdam

Destination of the week: Medellin

Colombia's second city sprawls in the lazily anarchic manner of many South American cities: it fills the Aburra valley, a fold in the central spine of the Andes a mile above sea level and seven degrees from the Equator. Medellin was founded in the 17th-century as a base for Basque gold miners and a refuge for Jews expelled from Spain. The city has a near-perfect climate, which usually feels like a fine early summer's day in England – and is perfect for growing orchids; the botanical gardens are, accordingly, splendid. Nearby attractions include a modest lake district (created to supply a hydro-electric plant), dominated by a 600-foot granite outcrop looking like a huge, decaying molar of a rock: El Penol. You can climb a staircase to the summit, revealing green hills, steely water and sparkling blue skies. Hitherto this fascinating part of South America has been difficult to reach; but from 3 July, Avianca will launch non-stop flights from Madrid, with easy connections from the UK.

Bargain of the week: 15 per cent off in England's deep south

Southern Railway, part-owned by the French railway enterprise, SNCF, has the rail franchise for much of Surrey, all of Sussex and parts of Kent and Hampshire. It also has plenty of innovative offers – such as a 15 per cent offer for advance tickets bought online rather than at the ticket office, providing a London-Brighton one-way ticket for just £4.25.

The latest deal will intrigue anyone travelling by rail in the region: a 15 per cent discount from off-peak fares, so long as you buying tickets online at southernrailway.com. Unlike almost all similar offers (eg the 10 per cent discount on East Coast Trains), they do not require advance purchase. So you can book now for a day-return to East Grinstead (for the Bluebell Railway) for £10.10, to Chichester for £19.40, or to Hastings for £20.30, and travel on any off-peak train.

Warning of the week: Thailand

Western diplomats are leaving the capital, Bangkok, after weeks of uprising culminated in violence and destruction this week. The US Department of State is sending away "all non-emergency US government personnel and eligible family members". The US government also goes beyond the current Foreign Office advice and "recommends against travel to Bangkok and non-essential travel to Thailand".

Tourists in other parts of Thailand who wish to come home early face potential problems. Bangkok airport is functioning normally, but with pressure on space aboard long-haul flights from Bangkok to Europe, it may be difficult for those who find a domestic flight from airports such as Phuket, Koh Samui or Chiang Mai to the capital to find an onward journey. The airport could be once again shut down as it was by protesters in 2008. Instead, it is worth seeing what options there are to fly to destinations outside Thailand - perhaps to Singapore, Kuala Lumpur or Hong Kong - and come back from there.

Several hundred thousand are likely to be booked to travel to Thailand in the coming months. On package holidays, the tour operator may offer an alternative destination, a postponement or a refund for imminent departures. Passengers with flight-only tickets booked are in a more awkward position: if the airline is still flying in, then it is not obliged to give a refund. BA, however, is offering refunds or rebooking to those due to travel to Bangkok imminently.

Tip of the week: Keep alert in Amsterdam

The Foreign Office has issued a warning with admirable precision about pick-pocketing and bag-snatching in the Dutch capital. "Thieves often operate in gangs on the trains to and from Schiphol airport and Centraal station, as well as on the trams. While one thief will attempt to distract you (often by asking for directions or by banging on your window) another picks your pocket or steals your bag. Newly arrived and heavily laden passengers are a particular target."