The most appropriate one-word substitution for "a group of islands and sea around them" is archipelago.

• Archaeology is the study of human history and prehistory through the excavation of sites and the analysis of artifacts.
• Anthropology is the study of human beings and their cultures.
• Monologue is a long speech by one person during a conversation that stops other people from speaking or expressing an opinion.

The word archipelago comes from the Greek words "arkhe" (chief) and "pelagos" (sea). An archipelago is a group of islands that are close together and are surrounded by sea. The Hawaiian Islands, the Philippines, and the Maldives are all examples of archipelagos.