Related Clues:

• Type of fly ball
• Like some thoughts
• Low-pitched
• Six preceder
• Unfathomable
• Thought-provoking
• Shallow's opposite
• Requiring much thought
• Like an abyss
• See 113-Down
• __-sea
• ___ blue sea
• Worth thinking about
• Like the 10-foot end of the pool
• Way down