Problems of littering are one of the factors, but one of the main concerns for oceans is overconsumption.
The world's huge demand for fish has lead fish being removed from the ocean faster than they can reproduce. Ironically, we even take their eggs, and turn it into delicacies. Many of the world's fish species are suffering from problems caused by overfishing, with large imbalances in the ecosystem created.
Coral reefs may be considered the rainforests of the ocean, essentially a ‘forest of fish' and of course, coral. As travellers, these habitats are likely to be ones most affected by our actions, as they are often seen as a tourist attraction. However, tourists are often the reason for the destruction of these reefs, mainly due to lack of understanding.
Many boats that carry tourists to snorkelling sites often scratch coral surfaces and destroy them; ships with anchors sometimes drop them straight into reefs. Another danger to coral is that it is often collected. Although it may seem harmless to take a small piece, one might realise that these are likely to be the same thoughts of the millions of other tourists that visit the reef each year. Tourists and boats may also carelessly bring sediment to the surface, and by doing this reduce the sunlight penetration, as well as possibly cause of erosion through abarasion of sediment against coral.
As travellers, we are often exposed to these, and possibly encouraged to participate in them due to lack of understanding. We can make the choice not to be a partner in damaging the oceans. When we are tempted to indulge in foods such as caviar and rare fish, which might occur particularly during our holidays, remember that this means that we are part of the huge demand that causes overfishing of the oceans.