🔍 Key Concepts

• Pack ice vs. icebergs – understand how each forms and where they’re usually found • Optical and sea-surface signs of ice such as ice blink and swell/wave behavior • Difference between biological indicators (animals) and physical indicators (ice, waves, sky)

💭 Think About

• Ask yourself: which of these choices is clearly a visual or physical sign caused directly by nearby ice affecting light or sea state? • Consider: does the presence of an animal always guarantee ice is close, or can it range far from the actual ice edge? • Think about which option would a navigator be trained to watch for in textbooks and ice navigation guidance as a standard indicator of pack ice.

✅ Before You Answer

• Verify which listed items are directly caused by ice reflecting light or altering the sea state • Check which option is not a standard textbook/ice-navigation term used to describe an indication of nearby pack ice • Ask whether the indicator would be reliable and consistent enough for navigators to use in voyage planning and lookout procedures