Dear Tom,Thanks for your letter. It was great to hear from you! I am glad you enjoyed your trip to Niagara Falls; it sounds like an amazing experience.Russia has many beautiful water sights to offer. You should definitely visit Lake Baikal, which is the deepest lake in the world, or the stunning Ruskeala waterfalls in Karelia. As for me, I have never gone rafting, but I would love to try it someday. Generally, I think extreme sports are exciting because they help people test their limits and get an adrenaline rush, though they can be quite dangerous.Your upcoming trip to Greece sounds wonderful! Which cities are you planning to visit there? Will you be staying near the sea or in the mountains? Are you going to visit any ancient historical sites?Write back soon.Best wishes,Alex