Thousands of years ago, people looked out across an ocean and asked themselves, ’What is on the other side?’ And the bravest of them began to travel and find the answers – beautiful islands, frozen lands, different peoples... And there are still interesting questions about the oceans. How do they change our weather? Why does the water go up and down twice a day? Why do most animals and plants live near the land? And what can possibly live at the bottom of the ocean, thousands of metres down, where there is no light? Surely nothing can stay alive in a place like that... 'Factfiles' are a sub-series of 'Bookworms' with a non-fiction angle providing factual information for students on a wide variety of themes. Exercises at the back of each book check students' understanding of the text and provide ideas for activities and project work. Key features •All 'Oxford Bookworms Library' titles are fully illustrated. •The Activities section at the back of each title has been extended to include extra activities before, while and after reading, helping students to interact with the text and get the most out of each story. •Each title also has an Introduction, a Glossary of key topic words, and an informative 'About the Author' section.