When it comes to fundraising for worthy causes, travel agency owner Karen Simmonds has probably done more than her fair share.

But her latest venture, to jump into the freezing cold water of Brockwell Lido, south London, in the middle of December, will be one of her most daring events for charity to date. The Freeze for Trees event is to raise money for the charity Trees for Cities, one of the agency’s partners, which works on tree-planting projects in urban areas worldwide from Peru to Bolivia.

It follows one of her staff, Silvia McBride, joining a 10K run in aid of Tourism Concern.

“It’s my turn to do something radical,” says Karen, who will be wearing just a swimming costume to jump into the unheated lido. vKaren has set up a JustGiving page and hopes to canvass support from customers and the trade for the event.

It will not come as a surprise to those who know Karen. Six years ago she started an ongoing campaign, Make Travel Matter, to raise awareness of the positive impact of their holidays.

“We are all stewards on the planet and we have a duty to look after each other. An agent on the frontline can help people make informed holiday choices.”

This might mean suggesting clients consider holidays that include visiting local restaurants and communities, rather than all-inclusives, which can involve only eating within a resort.

Already the agency works with a number of partners including Tourism Concern, The Travel Foundation and Lata Foundation to spread the word about worthy causes.

“We go to schools to give talks and put messages in our communications with clients. We work with a business that specialises in pre-school entertainment and they have designed a booklet for our customers with young children with travel tips in it.”

But for the next 10 days Karen will be focused on swimming in freezing cold water in the middle of winter.

“I’m not a scientist but to me the gesture of planting trees is better than calculating your carbon footprint – and it’s an easy message to get across.”

Support Karen by going to justgiving.com/Karen-Simmonds2