There are several types:
The name of the scientist that studies artifacts remains of cultures from the past is an archeologist.
Marine biologist. Actually, a Marine Biologist is someone who studies marine organisms (plants, oceans, and animals), but someone who studies MAINLY marine mammals is a marine mammalogist.
An archaeologist(the study of the past by studying artifacts)
The name for someone who studies caves is a speleologist or a spelunker.
An archaeologist is the scientist who discovers and studies ancient artifacts. They use various methods to excavate, analyze, and interpret these artifacts to learn about past human societies and cultures.
A scientist who studies water (H2O) would be a hydrologist or a water chemist.
The name of a scientist that studies sports is called a sports scientist.
A scientist who studies floods is called a hydrologist. Hydrologists study the distribution, movement, and properties of water on Earth.
A virologist is a scientist who studies viruses.
An arachnologist
A scientist who studies animals is called a zoologist.
A scientist who studies radioactivity is called a nuclear physicist or a radiologist.
A scientist who studies animal life is a zoologist. There is no particular name for a scientist that specialises in platypuses.
Hydrologist
The name for this type of scientist is a teuthologist
This answer is a entomologistA scientist who only studies fish is called an ichthyologist.
A hydrologist is a scientist who specializes in studying water, including its distribution, movement, and quality in the environment. They often focus on aspects of the water cycle, such as precipitation, evaporation, and groundwater flow.