Something To Declare: America gets tougher; long-haul ferry deals; Slovenia, underground; Oberammergau

Warning of the week: America gets tougher

The cost and inconvenience of reaching the US steps up again this week – but holidaymakers and business travellers considering a transatlantic trip in the next two years can dodge the new financial penalty by applying for permission by next Tuesday, 7 September.

On Wednesday, the Electronic System for Travel Authorisation (ESTA) changes from a free service to one that will cost $14 (nearly £10) per person. But permission to enter the US lasts for two years, which means the ESTA will expire at the end of the summer of 2012. You can re-apply even you have a current ESTA.

Beware of simply tapping "ESTA" into a search engine, because the first few entries will be commercial ventures seeking to get you to pay more. Instead, use this link: www.bit.ly/cl5Hlb.

Bargain of the week: Long-haul ferry deals

Now the summer holidays are over, the operators of longer-distance ferry crossings are cutting their fares in order to boost their traffic.

Stena Line is selling space on its Harwich-Hook of Holland route for as little as £49 each way for a car plus driver, with an extra £12 each way for additional adult passengers; book online at stenaline.co.uk to avoid a £10 charge for phone bookings.

Norfolkline is selling its Rosyth-Zeebrugge link for £80 each way for a car plus two ( norfolkline.com).

The new Nantes/St-Nazaire to Gijon service that starts on Wednesday is run by GLD Atlantique, a joint venture between LD Lines of Paris and Grimaldi Lines of Naples (book at gldatlantique.co.uk).

The opening offer for the 14-hour journey between western France and northern Spain is £79 each way for a car plus two, including a cabin.

Destination of the week: Slovenia, underground

If the prospect of 48 hours in Ljubljana tempts you to Slovenia, extend your stay – and ignore the weather – by heading underground, writes Norm Longley, author of the Rough Guide to Slovenia (£13.99).

With more than 7,000 caves catalogued, Slovenia boasts some amazing subterranean systems. Most are located in the Karst, a stony limestone plateau bordering Italy in the south-west corner of the country. The immense underground canyon of Skocjan – pictured – ( park-skocjanske-jame.si; tours hourly 10am-5pm, €14) is Slovenia's most memorable natural wonder.

At Postojna ( postojna-cave.com; tours 9am-6pm, €20), hop aboard a cave train that hurtles through enormous chambers to a complex of brightly lit grottoes stuffed with stalactites and stalagmites.

Tip of the week: Oberammergau

This Bavarian village stages Passion Plays only once a decade. The present season ends four weeks tomorrow; miss it, and you will have to wait until 2020. But some tickets are still available.

Through the German specialist DER Travel Service (020-7290 1111; dertour.co.uk), a package with Lufthansa flights from Heathrow to Munich, rail travel from the airport to Oberammagau, meals and a room in a private home costs £779 – including category 2 tickets for one performance.