Humminbird 698ci HD SI Combo Operation Manual page 41

The main benefit of Side Imaging® sonar to anglers is that it provides an overall
survey of a large area of water. This gives you a better understanding of the
bottom topography and how structure is oriented for more efficient fishing.
Saltwater anglers pick up precise details of popular fishing structure like
wrecks, reefs, humps, and drop-offs, as well as being able to spot bait balls in
open water. Freshwater anglers can see fish-attracting structure such as
timber, stumps, rocks, and creek beds.
29 What's on the Side Imaging® Display
Side Imaging®
sonar echoes are
first displayed at
the top of the
screen, and
historical data
scrolls down the
display as new
information is
received.