In the past 30 years, the number of literatures on oceanography continued to grow. Literature analyses on the sub-fields of oceanography have been published, including ocean remote sensing and ocean circulation. However, research on the entire field of oceanography is missing due to the difficulty of dealing with large collections of scientific text before the wide application of big data and deep learning. The development of big data and deep learning in recent years makes it possible for us to analyze literature in a higher dimension and a wider range, that is, the entire oceanography field. This study aimed to investigate the global research trends and research hotspots of oceanography based on more than 334,765 publications from the Web of Science from 1992 to 2021 by using a bibliometric analysis method and VOSviewer visual software. We show that publications have been continually increasing since 30 years ago, especially the past 10 years. Cluster analysis shows that ocean models, ocean variability, and phytoplankton are the main research hot keywords. Precipitation, climate change, water resource, and ocean circulation are the keywords with rapid growth in the last decade. In addition, we use a multi-label classification model to classify 334,765 publications into seven sub-fields. The analysis of time trend shows that the proportion of the two sub-fields, Meteorology & Atmospheric Sciences and Water Resources, is increasing with time. Based on this, we use the topic model BERTopic to draw a topic map of over 334,765 publications on oceanography to illustrate the thematic evolution in the past 30 years. The rapidly growing topics include precipitation and climate, which proves that the upsurge of climate change research in the past few years is also reflected in the oceanography, and that oceans are an important part of climate change. This paper reveals underlying patterns in scientific publications, research field, research topics based on more than 334,765 publications, which can serve as a summary of global research history on oceanography and a potential basis for future research.