Simplify the following text for a Grade 7 native English-speaking person.
Original: At first , all goods arriving by sea or being sent by sea had to be carried by porters between LÃ opoldville and Matadi , the port below the rapids and 150 k from the coast .
Simplified: At first , all goods arriving by sea or being sent by sea had to be carried by porters between LÃ opoldville and Matad .