The largest island in a lake on an island in a lake on an island is a nameless 1.6-hectare (4-acre) island at 69Â°47â²35â³N 108Â°14â²28â³W / 69.793Â°N 108.241Â°W / 69.793; -108.241, 121 kilometres (75 mi) inland from the south coast of Victoria Island, Canada.
A tsunami can travel across the open ocean at about 500-miles per hour, the speed of a jet airliner. As the wave approaches land and as the ocean shallows, the wave slows down to about 30 miles-per-hour and grows significantly in height (amplitude).
1 Some tsunamis can be very large. 2  In coastal areas their height can be as great as 30 feet or more (100 feet in extreme cases), and they can move inland several hundred feet. 3  All low-lying coastal areas can be struck by tsunamis. 4  A tsunami consists of a series of waves. 5  Often the first wave may not be the largest. Offshore reefs and shallow areas may help break the force of tsunami waves, but large and dangerous wave can still be a threat to coastal residents in these areas. 2  Staying away from all low-lying areas is the safest advice when there is a tsunami warning.