Kate Simon: Where you take your holiday can become a point of principle

Should tourists boycott Israel? Last week's storming of a merchant ship taking aid to Gaza by the Israeli armed forces once again raises this controversial question.

Israel's treatment of the Palestinians has long provoked heated debate about whether or not the international community should boycott Israeli goods and services to force a change of attitude. Following the deadly attack on the aid convoy, it won't just be hardened lefties thinking twice about visiting Israel.

Whether or not you agree with taking such action against Israel, do tourism boycotts work anyway? Certainly, an individual making a decision not to holiday in a particular destination isn't as effective as a co-ordinated general boycott by the world's most powerful nations. Then again, doesn't one lead to the other?

The independent UK charity Tourism Concern has been trying to persuade tour operators, guidebook publishers and tourists not to contribute to the coffers of Burma since 1998 because of the military junta's repressive rule, following a call for a boycott by the Burmese opposition. The campaign group says that it is "virtually impossible" to travel in Burma without contributing to the government, and claims its aim is to dent the $100m-plus (£68m) a year that flows from tourism and helps the generals to retain control.

Zimbabwe has been on the no-go list for years, too, in an effort to discourage lining the pockets of Robert Mugabe's rotten regime. This boycott is the subject of renewed debate. Just last week, the tour operator Bridge & Wickers announced its intention to encourage visitors back to the benighted African country, saying: "After a decade of decline and stagnation, there is a new spirit of optimism in Zimbabwe as the transitional government has begun to revive the moribund economy." And the guidebook publisher Bradt will also publish the first edition of its new guide to the country this month.

But it's not just dictatorships that attract tourism boycotts. Tourists to Turkey are accused by the Boycott Turkey Campaign of "propping up a regime that oppresses 15 million Kurdish people who live within its borders in a permanent state of emergency".

Canada is the subject of a long-term, high-profile campaign to stop seal hunting, of which a tourism boycott is a key part. And animal rights' groups have called for visitors to stay away from Alaska in the US because of a recent decision to remove buffer zones for wolf trapping (inset) near the Denali National Park.

You'll have noticed by now that these boycotts have achieved, at best, partial victories. South Africa during apartheid may be the only example of where a tourism boycott helped to influence wholesale change.

Yet, total triumph is not always the measure of success. For example, in the case of Burma, Tourism Concern believes that despite the fact that the generals are still in charge, the boycott has been successful. "The aim of the tourism boycott has not been to halt Burma's economy but to ensure that tourism was not directly contributing financially to the military junta. Tourist numbers to Burma are exceedingly low when compared [with] its south-east Asian neighbours."

While a tourism boycott in itself cannot provide a solution, it can be seen as a crucial step in any struggle for justice.

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