During the past 10 years, large developments and improvements on the technical possibilities and operational availability of full-size, Class III deep ocean work ROVs took place (> 3000 m). This is especially true for the marine science community. Where in the early 90’s scientific ROVs for ultradeep operations were a true technical challenge for technology leading institutions like IFREMER, MBARI, WHOI, and JAMSTEC, the sub-sea technology driving offshore oil and gas industry was orientated almost solely into developments for the shallow water production business. This relation changed dramatically with the achieved breakthroughs in ROV technology, some major of them developed by science institutions, and was adapted quickly into the 3000 m depth range increasingly provided by the underwater industry. However, ultra-deep, truly operational remote diving technology beyond 3000 m still remains a technical frontier both for industry and science. This paper addresses key issues emerging from such rapid developments for marine science, including inter-operability at different levels from vessel to payloads and procedures, at the same time cost and crew reducing/sharing demands, aspects of enhanced and effective training and testing, and new technical challenges to provide compatible scientific operations and data.