There are many dive operators here, both on Lembeh Island and on the mainland across the Strait. All of them are just a short distance from the top dive spots and many dives are made each day. They tend to be attached to resorts, some of which are quite upmarket and have excellent facilities. Certain operators can also arrange overnight trips to Bangka & Sanghige to the north.
Diving & accommodation are usually sold together as a package. Accommodation is usually in comfortable bungalows or chalets. There are very few budget accommodation options here.
The closest town to Lembeh Strait is Bitung. If you have arranged your trip in advance, your resort will normally meet you here. To get to Bitung, take a bus or taxi from Manado. Manado has a well-connected airport with flights from many spots in Indonesia, Singapore, Malaysia & the Philippines.
Aside from the diving, there is little else to do here. The resorts are well spread out and often all inclusive, so most guests are unlikely to leave the resort except to go diving. Back on the mainland around Manado, there are many activities, ranging from shopping & golf to trekking.