Rinse the split peas thoroughly and set aside.
In a large soup pot, combine split peas, water, and ham hock. Bring to a boil.
Reduce heat, cover, and simmer for 45 minutes, stirring occasionally.
Add carrots, celery, onion, potatoes, garlic, marjoram, and bay leaf.
Continue to simmer uncovered for another 45 minutes, or until peas and vegetables are tender.
Remove ham hock. Cut meat off the bone, chop, and return it to the soup.
Season with salt and pepper as desired.
Discard bay leaf and ladle soup into bowls. Garnish with fresh parsley.