Possible answers:

• Waste from pleasure boats, holiday homes, campsites and hotels contribute to eutrophication
• Boating and jet-skiing result in petrol and oil emissions
• Noisy activities such as pleasure boating and jet-skiing can disturb wildlife and especially during then breeding season
• The anti-fouling paints used on boats can be harmful to marine life
• Recreational fishing may harm fish populations
• Poor planning and unsuitable recreational land uses can destroy valuable habitats and landscapes
• Ground water reserves are being depleted due to high tourist demand
• Destruction and fragmentation of the living environment causes biodiversity loss