If you are of one of the nationalities currently exempt from visa for Thailand (30 or 45 days), any means of entry into the country (sea, air or land) is possible.
The nationalities concerned : South Africa, Andorra, Australia, Austria, Bahrain, Belgium, Brazil, Brunei, Canada, South Korea, Denmark, United Arab Emirates, Spain, Estonia, United States, Finland, France, Greece, Hong Kong, Hungary, Indonesia, Ireland, Iceland, Israel, Italy, Japan, Kuwait, Latvia, Liechtenstein, Lithuania, Luxembourg, Malaysia, Maldives, Mauritius, Monaco, New Zealand, Norway, Oman, Netherlands, Peru, Philippines, Poland, Portugal, Qatar, United Kingdom, San Marino, Singapore, Slovakia, Slovenia, Sweden, Switzerland, Czechia, Turkey, Ukraine, and Vietnam.
Visas issued also allow these means of entry.