Dreams often reflect our subconscious thoughts, emotions, and experiences. In your dream, several elements stand out that can offer insights:

1. Filthy Bathroom: A public bathroom, especially one that is dirty, can symbolize feelings of embarrassment, vulnerability, or a need to release negative emotions. It may suggest you're dealing with something unpleasant in your waking life.
2. Blood and Crocodile Head: Blood can represent deep emotional pain or unresolved issues, while the crocodile may symbolize hidden fears or aggressive instincts. The juxtaposition of these elements could indicate a struggle with something that feels overwhelming or threatening.
3. Tsunami: A tsunami often represents powerful emotions or situations that feel uncontrollable. It can signify a major change or upheaval in your life. Being on top of the tsunami suggests that you may feel capable of riding through challenging times, even if they feel overwhelming.
4. Green Land and Rising Sun: The transition to a green land and the rising sun signifies hope, renewal, and new beginnings. This part of the dream may symbolize a fresh start or a positive change following a difficult period.
5. Wearing Only Underwear: This can indicate a sense of vulnerability or exposure. It might reflect feelings of being stripped down to your essentials, facing your true self, or being unguarded in a new environment.

Overall, your dream seems to reflect a journey through turmoil and emotional challenges, leading to a place of renewal and hope. It could be an encouragement to confront your fears and embrace the changes in your life as opportunities for growth. Consider reflecting on any current challenges you’re facing and how you might navigate them toward a more positive outcome.