Related Clues:

• Mediterranean and Baltic, e.g.
• Word after open or seven
• Maria on Mars
• They can get high
• Salty expanses
• Word in many cruise ships' names
• Proverbial heptad
• A buttload
• Red and Black
• They may be high or heavy
• 'High' bodies
• Coal measures
• Aral and Arabian
• Caspian, and others
• Bajillions