Original: One chain extends across the sea to Chios, another extends across Euboea to Samos, and a third extends across the Peloponnese and Crete to Rhodes, dividing the Aegean from the Mediterranean.
Simplified: One chain goes across the sea to Chios, another one goes across Euboea to Samos, and a third one goes across the Peloponnese and Crete to Rhodes. This one divides (splits, cuts) the Aegean from the Mediterranean.