【Japan】
気象庁/潮位観測情報 (JMA's website, but you can see data from other institution)
国土地理院/潮位データ提供 国土地理院験潮場一覧 (GSI's website)
海上保安庁/リアルタイム験潮データ (JCG's website, but you can see data from other institution)
リアルタイムNOWPHAS (NOWPHAS's website)
【World】
* JMA = Japan Meteorological Agency
* GSI = Geospatial Information Authority of Japan
* JCG = Japan Coast Guard
* NOWPHAS = Nationwide Ocean Wave information network for Ports and HArbourS (operated by Ports and Harbours Bureau and other institution)
* IOC = Intergovernmental Oceanographic Commission of UNESCO
* DART = Deep-ocean Assessment and Reporting of Tsunamis
* PTWC = Pacific Tsunami Warning Center
To view/download past data.
【No Request & Approval Required】
Interval: 1 min
You will be redirected to a page where the data is arranged in a table format, but you can use it by copy-pasting it into a text file.
Some JMA data can be downloaded from here (since 2012). List of available JMA stations.
国土地理院/潮位データ提供 国土地理院験潮場一覧 (GSI)
Interval: 30 sec
Since 2006
You can download in text file format
NEAR-GOOS 地域遅延モードデータベース (JCG)
Interval: 30 sec (-2022) or 1 min (2023-)
Since 1996
You can download in text file format, but it's a bit difficult to read (1 month data is compiled)
【Request & Approval Required】
OBPG data from NIED. User registration is required.
JMA tidal gauge data
Some of them are available from IOC.
For major tsunami events, they are available in the form of figures in PDF; in the press release (since 2000) or the Monthly Report on Earthquakes and Volcanoes in Japan (since 1997).
If you want the original data, you need to inquire (I've never done this).
NOWPHAS
Data is provided after asking via e-mail
【Others】
Old tidal gauge data (microfilmed paper records)
【solver】